For writing, the Claude models still set the standard, and the current pick is Claude Sonnet 5.5. Anthropic built it for well-scoped everyday work, including polished documents and slides, and says it writes more clearly than Sonnet 5; at $2/$10 per million tokens it is also cheaper than its predecessor. Claude Opus 5.5 ($4/$20) is worth the extra cost for long, high-stakes pieces where the structure has to hold across thousands of words. If your team lives in ChatGPT, GPT-6.1 Sol is the strongest OpenAI option at the same $2/$10 price as Sonnet 5.5. For bulk drafts that an editor will rewrite anyway, Claude Haiku 5.5 and GPT-6 Luna both cost $0.10/$0.50.
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Rankings refresh dailyScored on 6 criteriaNo paid rankings
Best pick right now
AnthropicBalanced
Claude Sonnet 5.5
Near-Opus 5.5 quality on scoped work at half the price.
Claude Sonnet 5.5 holds tone and structure across long drafts and revisions, and Anthropic positions it specifically for polished documents, at half the price of Opus 5.5.
Claude Opus 5.5 is the step up for long-form work where an argument has to stay coherent over many sections — board papers, reports, and published articles.
Claude Haiku 5.5 and GPT-6 Luna at $0.10/$0.50 make high-volume first drafts cheap enough to run on everything, as long as a person edits the result.
Decision notes
Choose Claude Sonnet 5.5 for everyday professional writing — reports, proposals, articles and emails where quality matters and the work arrives in a steady stream.
Choose Claude Opus 5.5 when the piece is long and the stakes are high: executive communications, thought leadership, or anything where average output is not acceptable.
Choose GPT-6.1 Sol when your team already works in ChatGPT or needs its built-in tools; switching providers for writing alone rarely pays off.
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#1Claude Sonnet 5.593 pts
#2Claude Opus 5.592 pts
#3Claude Fable 5.191 pts
#4GPT-6 Astra91 pts
#5Claude Mythos 5.190 pts
Quality first
Claude Sonnet 5.5
Anthropic / Balanced / Oct 10, 2026
93
Near-Opus 5.5 quality on scoped work at half the price.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
Strengths
Terminal-Bench 4.0 70.6% in Anthropic's table — above Opus 5.5's 66.4% on that row
Half the price of Opus 5.5 at $2/$10, with cache reads cut to $0.10/1M
Anthropic says it generates more than 30% faster than Sonnet 5
Weaknesses
Anthropic itself says Opus 5.5 is better on loosely defined tasks that need longer reasoning
Trails Opus 5.5 on Humanity's Last Exam (64.5% vs 67.7%)
Ranked alternatives
Strong backups depending on your budget, workload, and preferred tradeoffs.
AnthropicPremium
Claude Fable 5.1
Anthropic's September 1, 2026 frontier release for coding, agents, and scientific work. On SWE-bench Pro the cheaper Claude Opus 5.5 now scores higher (89.9% vs 81.2% in Anthropic's table). Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
Verdict
Anthropic's highest-ceiling model — strongest on open-ended research; Opus 5.5 now leads coding.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
OpenAI's September 3, 2026 frontier release — the first GPT-6 model and OpenAI's answer to Claude Fable 5.1 two days earlier. State of the art on computer use (OSWorld 2.0 72.6% in ~47% less time than GPT-5.6 Sol), agentic coding (Terminal-Bench 4.0 57.9%), and frontier math (FrontierMath Tier 4 97.6%). $10/$50 per 1M tokens, 1.05M context, 128K output, knowledge cutoff April 30, 2026.
Verdict
OpenAI's frontier answer to Fable 5.1 — computer-use and agentic-coding leader at $10/$50.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1.1M tokens
Released September 3, 2026. API ID gpt-6-astra; rolling out over the coming days to ChatGPT Plus, Pro, Business and Enterprise (usage inside existing allowances; GPT-6 Astra Pro for Pro/Business/Enterprise; Enterprise off by default), the OpenAI API, Microsoft Azure and Amazon Bedrock. Standard API pricing $10/$50 per 1M tokens; Fast mode is up to 2x speed at 2x price; cache reads and writes have separate rates. Model docs list 1,050,000 context, 128,000 max output, knowledge cutoff April 30, 2026, reasoning efforts up to 'max'. Published launch numbers (Astra / GPT-5.6 Sol / Fable 5.1 / Opus 5): OSWorld 2.0 72.6 / 65.7 / — / 70.2; Terminal-Bench 4.0 57.9 / 37.3 / 55.8 / 52.3; Terminal-Bench Science 0.1 64.6 / 22.4 / 52.6 / 30.0; FrontierMath Tier 4 v2 97.6 / 83.0 / 87.8 / 73.2; GPQA Diamond 96.0 / 94.6 / 93.7 / 93.7; Humanity's Last Exam w/ tools 57.2 / — / 65.0 / 63.6; AutomationBench 41.4 / 18.1 / 31.4 / 26.9; DeepSWE v1.1 74.1 / 72.7 / 67.4 / 73.7; ARC-AGI-2 95.0 / 92.5 / 90.0 / 90.4; ARC-AGI-3 99.9 (OpenAI responses-API harness; ARC Prize's stateless runs score far lower) / 7.8 / — / 30.2; ExploitBench 100.0 / 78.5 / — / 70; SRE-Bench 88.0 / 55.9; Artificial Analysis Intelligence Index v4.1.1 61.2 / 60.9 / 65.7 / 63.1. Meets the Critical threshold for cybersecurity under OpenAI's Preparedness Framework; advanced cyber workflows gated behind OpenAI Daybreak. All figures from OpenAI's launch post and model docs, verified September 4, 2026.
Computer use leaderFrontierAgenticReasoningLong contextPremiumNew
Best for
Computer and browser use, long-horizon agentic coding, and frontier math and science work
Anthropic's September 22, 2026 Opus — a step up from Opus 5 on agentic coding, long-running agent work and vision, at a lower $4/$20 list price and with fewer tokens spent per finished task.
Verdict
Anthropic's new coding default — top SWE-bench Pro score at a lower price than Opus 5.
Quality score
98%
Pricing
$4.00/1M in
$20.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 22, 2026. Gateway id anthropic/claude-opus-5.5. $4/$20 per 1M (cache read $0.20, cache write $5); Fast mode $8/$40. 1,000,000 context, 128,000 max output, knowledge cutoff June 2026, effort levels low to max. Launch figures as reported by Anthropic: SWE-bench Pro 89.9 (Fable 5.1 81.2, Opus 5 79.2); SWE-bench Multilingual 93.9; Terminal-Bench 4.0 66.4 (xhigh); OSWorld 2.1 81.8; Humanity's Last Exam 67.7; Toolathlon Verified 77.8 (Opus 5 80.6). Verified October 10, 2026.
CodingAgenticFlagship1M contextPremiumNew
Best for
Agentic coding, long-running agents and knowledge work where Opus 5 was the bar
The unrestricted twin of Claude Fable 5.1 — the same model with safeguards lifted in high-risk areas, released September 1, 2026 to vetted cybersecurity and life-sciences organisations under Anthropic's trusted-access programme. Scores 60.9% on Terminal-Bench 4.0, the highest agentic-coding result Anthropic has published.
Verdict
Fable 5.1 with the safeguards lifted — partner-only, 60.9% Terminal-Bench 4.0.
Quality score
97%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 1, 2026 alongside Claude Fable 5.1, continuing the Mythos-class line that began with Project Glasswing's April 2026 private preview. Access is limited to vetted US cybersecurity and life-sciences professionals. Same underlying model, pricing, context window, and cache-read discount as Fable 5.1; the only published difference is the safeguard level and the resulting Terminal-Bench 4.0 score (60.9% vs 55.8%).
Our pick for writing. It scores 98/100 on the writing axis we weight this page by, and nothing else in this shortlist matches it on output quality.
Anthropic's September 28, 2026 Sonnet — built for well-scoped everyday work like features, bug fixes, documents, slides and spreadsheets, priced at $2/$10 and close to Opus 5.5 on most of Anthropic's launch rows.
Input
$2.00/1M
Output
$10.00/1M
Context
1M tokens
Speed
Fast
What people actually use it for
Day-to-day feature and bug-fix work in an IDE or coding agent, where speed matters more than ceiling
Drafting documents, slide decks and spreadsheets that need to be presentable on the first pass
Computer-use tasks — Anthropic reports 80.1% on OSWorld 2.1, within two points of Opus 5.5
Where it wins
Terminal-Bench 4.0 70.6% in Anthropic's table — above Opus 5.5's 66.4% on that row
Half the price of Opus 5.5 at $2/$10, with cache reads cut to $0.10/1M
Anthropic says it generates more than 30% faster than Sonnet 5
Where it falls down
Anthropic itself says Opus 5.5 is better on loosely defined tasks that need longer reasoning
Trails Opus 5.5 on Humanity's Last Exam (64.5% vs 67.7%)
Skip it if
The work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much.
Our verdict
The model most people should default to in the Claude lineup. Sonnet 5.5 lands within a few points of Opus 5.5 on most of Anthropic's launch rows, beats it on Terminal-Bench 4.0, and costs half as much. Step up to Opus 5.5 only when the task is open-ended and long.
Here for latency: it answers fastest of anything listed for writing, at 98/100 on writing.
Anthropic's September 1, 2026 frontier release for coding, agents, and scientific work. On SWE-bench Pro the cheaper Claude Opus 5.5 now scores higher (89.9% vs 81.2% in Anthropic's table). Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
Input
$10.00/1M
Output
$50.00/1M
Context
1M tokens
Speed
Deliberate
What people actually use it for
Agentic scientific research — 52.6% on Terminal-Bench-Science 0.1, more than double Fable 5's 24.7%
Long-running autonomous coding agents that plan, run, and debug across a whole repository
Cache-heavy agent loops where the 75% cache-read cut ($1.00 → $0.25 per 1M) is the real saving
Where it wins
52.6% Terminal-Bench-Science 0.1 — 2.1x Fable 5 (24.7%), well clear of Opus 5 (29.0%) and GPT-5.6 Sol (22.4%)
55.8% Terminal-Bench 4.0 agentic coding, ahead of Opus 5 (52.3%) and Fable 5 (42.0%)
Cache reads cut 75% to $0.25/1M — ~25% cheaper for typical use, ~45% for heavily agentic work
Independent Vals AI evaluation ranks it #1 of 51 on the Vals Index, #1 on LiveCodeBench (90.5%) and MMLU Pro (92.4%)
1M-token context and 128K max output at standard rates, with adaptive thinking always enabled
Where it falls down
Base rates are still $10/$50 per 1M — double Claude Opus 5 for anything that is not cache-heavy
Anthropic published no SWE-bench Verified or SWE-bench Pro figure for 5.1 at launch
On Claude Pro it only runs on pay-as-you-go credits; Max includes it up to 50% of weekly limits
Deliberate, high-latency profile — the wrong choice for interactive, latency-bound apps
Skip it if
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
Our verdict
Anthropic's highest-ceiling model, and the rare upgrade that costs less than the model it replaces — though for coding alone, Claude Opus 5.5 now scores higher at $4/$20. Base $10/$50 pricing did not move, but a 75% cut to cache reads makes typical workloads ~25% cheaper than Fable 5 and heavily agentic ones ~45% cheaper — while more than doubling Fable 5 on agentic science and beating Opus 5 on agentic coding. If you were already on Fable 5, switching is a straight win. If you were on Opus 5 for the price, it still costs 2x on uncached tokens.
Rounds out the shortlist for writing at 97/100 on writing.
Input
$4.00/1M
Output
$20.00/1M
Context
1M tokens
Speed
Deliberate
Anthropic's new coding default — top SWE-bench Pro score at a lower price than Opus 5. Full Claude Opus 5.5 review →
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FAQ
What is the best AI for writing?
For writing, Claude Sonnet 5.5 (Anthropic) is our pick. Near-Opus 5.5 quality on scoped work at half the price. It costs $2/1M input and $10/1M output tokens, with a 1M-token context window — enough headroom for all but the largest writing jobs. Claude Fable 5.1 is the closest alternative if it doesn't fit your setup.
Why Claude Sonnet 5.5 for writing?
Because the work it is built for overlaps closely with writing: day-to-day feature and bug-fix work in an IDE or coding agent, where speed matters more than ceiling and drafting documents, slide decks and spreadsheets that need to be presentable on the first pass. The model most people should default to in the Claude lineup. Sonnet 5.5 lands within a few points of Opus 5.5 on most of Anthropic's launch rows, beats it on Terminal-Bench 4.0, and costs half as much. Step up to Opus 5.5 only when the task is open-ended and long.
What does it cost to use Claude Sonnet 5.5 for writing?
On a moderate month — 10M input and 2M output tokens — Claude Sonnet 5.5 runs about $40.00 at list price, with no batch or caching discounts applied, so treat that as a ceiling. It is also the cheapest option among the models compared here, so for writing there is no cost argument for dropping to something weaker.
When is Claude Sonnet 5.5 the wrong choice for writing?
Anthropic itself says Opus 5.5 is better on loosely defined tasks that need longer reasoning. Trails Opus 5.5 on Humanity's Last Exam (64.5% vs 67.7%). Avoid it if the work is long, ambiguous and multi-step — Anthropic positions Opus 5.5 for exactly that — or you need the lowest possible price, where Haiku 5.5 costs a twentieth as much. None of that rules it out for writing on its own — but if one of those limits maps onto how you actually work, take the alternative on this page seriously rather than defaulting to the top pick.