Best LLM for Each Task: Which AI Model to Use (Oct 2026)

The best LLM for each task depends on the job, and on 4 October 2026 the public evidence points to clear starting points. Anthropic's Claude models sit at or near the top of most LMArena boards we checked, OpenAI's GPT-6.1 Sol and Google's Gemini 3.8 Flash offer far lower prices for everyday work, and Qwen3.8-27B or Gemma 4 are realistic choices to run on your own computer. Test on your own prompts, and expect the rankings to change monthly.

How do you pick the best LLM for each task?

We combined three kinds of evidence, all read on 4 October 2026. LMArena collects human votes on anonymous answers and publishes scores with margins of error. Its boards used here are dated 24 August to 2 October 2026. Artificial Analysis publishes an Intelligence Index, a composite of its own tests, plus cost per task and output speed. Vendor pages give prices, context windows and tools: Anthropic, OpenAI and Google.

Benchmarks disagree. Gemma 4 31B ranks 76th on LMArena's overall text board but scores 15 on Artificial Analysis's index, against 58 for the top entry, because one measures human preference and the other measures task performance. Many top LMArena scores also sit inside each other's margins, so ranks 2 to 7 on the text board are effectively tied. Entries marked Preliminary have fewer votes so far and may still move.

One model needs a warning. Google announced Gemini 4 Argon on 30 September 2026 and it tops several LMArena boards as a preliminary entry, but Google says it is rolling out to trusted cyber defenders first, with developers and subscribers to follow. We do not recommend it for general use until it is available.

Model	API price per million tokens, input / output	Context window
Claude Fable 5.1	$10 / $50	1M tokens
Claude Opus 5.5	$4 / $20	1M tokens
Claude Sonnet 5.5	$2 / $10	1M tokens
GPT-6 Astra	$10 / $50	1.05M tokens
GPT-6.1 Sol	$2 / $10	1.05M tokens
GPT-6 Luna	$0.10 / $0.50	1.05M tokens
Gemini 3.8 Flash	$0.75 / $3.75 until 31 Dec 2026, then $1.50 / $7.50	1M tokens (LMArena listing)

These are API prices from the vendor pages. Chat subscriptions are priced separately, and each vendor offers a free tier with limits.

Which AI model is best for which task?

Task	Strong picks	Evidence	Main trade-off
Writing	Claude Opus 5.5, Gemini 3.8 Flash	LMArena Creative Writing, 2 Oct: Opus 5.5 second, Gemini Flash models fifth and seventh	Opus costs more; Flash ratings are preliminary and its price doubles in 2027
Coding	Claude Opus 5.5, GPT-6 Astra, GPT-6.1 Sol	LMArena WebDev, 1 Oct: first, second and fourth	Astra costs $10 / $50; leaders are close
Research with sources	OpenAI Sol line, Claude Opus, Gemini with Google Search	LMArena Search, 24 Aug: first, second and fourth, Gemini ninth	Snapshot predates the newest models
Data analysis	ChatGPT, Claude, Gemini with code tools	Vendor documentation	No independent leaderboard found
Long documents	Claude Opus 5, Claude Fable 5.1, GPT-5.5	LMArena Document, 13 Sep: first, second and eighth	Large windows still need quote checks
Translation, including Romanian	Claude Opus 5.5, Claude Fable 5.1, Gemini 3.7 Flash	LMArena Non-English, 2 Oct: third, second and tenth	No Romanian board exists
Image understanding	Claude Fable 5, GPT-6.1 Sol, Gemini 3.8 Flash	LMArena Vision, 2 Oct: first, tenth and eleventh	Top scores are tied; Fable is the priciest
Voice	GPT-Live 1, Gemini 3.8 Live, Gemini 3.8 Flash TTS	Vendor documentation; Artificial Analysis Speech Arena: TTS fourth	No independent voice-chat ranking found
Quick everyday questions	Gemini 3.8 Flash, GPT-6 Luna, Claude Sonnet 5.5	Artificial Analysis speed and cost; LMArena text eighth for Flash	Less depth on hard problems
Running locally	Qwen3.8-27B, Gemma 4 31B, Gemma 4 12B	Ollama sizes; Artificial Analysis index 34, 15 and 14	Hardware needs; gap to cloud models

What is the best AI for writing and everyday questions?

Writing

On the LMArena Creative Writing board (2 October), Claude Opus 5.5 ranks second at 1516, behind only the unreleased Gemini 4 Argon preview. Claude Fable 5 ranks third at 1503. Gemini 3.7 Flash and 3.8 Flash rank fifth and seventh, both preliminary, at $0.75 / $3.75 per million tokens. OpenAI's best entry, GPT-5.6 Sol, sits at 19th. Anthropic recommends Opus 5.5 as the starting point for most workloads. The trade-off is price, since Opus 5.5 costs about five times as much as Gemini 3.8 Flash per output token.

Quick everyday questions

Speed and price matter more here than the last few points of quality. Artificial Analysis measures Gemini 3.8 Flash at 249 tokens per second, against 93 for Claude Opus 5.5 at maximum effort, and GPT-6 Luna at about $0.07 per task on its index. Gemini 3.8 Flash also ranks eighth on the LMArena text board. Anthropic describes Sonnet 5.5 as its best mix of speed and intelligence. Use these for lookups, rewrites and quick explanations, and move up a tier when an answer looks shaky.

What is the best AI for coding and data analysis?

Coding

On LMArena's WebDev board (1 October), Claude Opus 5.5 leads at 1815, GPT-6 Astra is second at 1788 and Claude Sonnet 5.5 third at 1786, with GPT-6.1 Sol fourth at 1758. The margins are about 10 to 18 points, so the leaders are close. Artificial Analysis puts Opus 5.5 first on its index at 58, with Astra at 53 and Sol at 52. Cost differs sharply: its cost per task is $5.98 for Opus 5.5 at maximum effort, $1.82 at high effort, $3.26 for Astra and $0.72 for Sol. OpenAI describes Sol as near-Astra performance at a lower cost. For plans and open models, see our guides to AI coding subscriptions and the best open-weight coding models.

Data analysis

We found no independent leaderboard for spreadsheet analysis, so choose by tools. OpenAI's help page lists a data analysis tool for accurate calculations and charts. Anthropic's help centre documents code execution for CSV analysis, Python scripts and charts. Google's developer guide recommends code execution for any arithmetic. Ask the tool to show its code and the numbers it used, and spot-check totals.

What is the best AI for research, long documents and images?

Research with sources

On the LMArena Search board (24 August, before the newest releases), GPT-5.6 Sol ranks first at 1257, Claude Opus 4.6 second at 1253 and Claude Opus 4.7 fourth. Gemini 3.1 Pro with grounding ranks ninth. Votes measure preference, not whether each citation is right, so open the sources and read our guide to AI hallucinations. Claude's Research mode needs a paid plan and web search, and Anthropic warns that research sessions can use up your limits faster.

Long documents

On the LMArena Document board (13 September), Claude Opus 5 ranks first at 1516, Claude Fable 5.1 second at 1513 and GPT-5.5 eighth at 1486. Gemini models rank lower on that board, from about 20th. Anthropic lists 1M-token windows for Fable 5.1, Opus 5.5 and Sonnet 5.5, and OpenAI lists 1.05M for the GPT-6 family. A large window does not guarantee accurate recall, so ask for quotes before conclusions.

Image understanding

On LMArena's Vision board (2 October), Claude Fable 5 ranks first at 1309, GPT-6.1 Sol tenth at 1291 and Gemini 3.8 Flash eleventh at 1290, preliminary, at $0.75 / $3.75. The first-place score could land anywhere from rank 1 to 10 within its margin, so price and your own test images should decide.

Which AI is best for translation, including Romanian, and voice?

Translation

LMArena has boards for German, French, Spanish, Russian, Chinese and non-English prompts, but no Romanian board, and we found no vendor publishing a Romanian-specific score. On the Non-English board (2 October), Claude Fable 5.1 ranks second at 1495, Claude Opus 5.5 third at 1494 and Gemini 3.7 Flash tenth at 1484, preliminary. Translate a 300-word sample of your own text with two models, name the target language and register, and ask for ș and ț with comma-below diacritics. For whole files, see our guide to translating documents while keeping formatting.

Voice

For live conversation, OpenAI describes GPT-Live 1 as its premier model for natural, expressive voice conversations with smooth interruption handling, and Google calls Gemini 3.8 Live its default model for low-latency voice agents. We found no independent ranking of voice chat. For text-to-speech, the Artificial Analysis Speech Arena ranks Eleven v4 first at 1321 ($80 per million characters) and Gemini 3.8 Flash TTS fourth at 1275 ($16.50), a fifth of the price.

Which model should you run locally?

Local models keep text on your device and cost no per-token fees, and they are noticeably weaker than the cloud leaders. Ollama lists Qwen3.8-27B at 18 GB with a 256K context and image input, and Artificial Analysis scores it 34. The Gemma 4 family runs from 4.6 GB to about 20 GB, with the 12B model at 7.7 to 8.0 GB. Gemma 4 31B scores 15 on the index and the 12B model scores 14. LMArena lists Qwen3.8-27B and Gemma 4 31B as Apache 2.0. Plan for more memory than the file size, because context needs room too. Read about the privacy trade-offs in our guide to AI chatbot privacy settings.

ChatGPT vs Claude vs Gemini: which should you pick?

This is our reading of the evidence above. Claude suits long writing, document review and coding, and its top models cost more per token than GPT-6.1 Sol or Gemini 3.8 Flash. ChatGPT suits search-backed research, where an OpenAI model holds the top Search board result. Gemini Flash suits cheap, fast everyday work. Many people do best with one paid assistant for daily work, a free tier of a second one for cross-checks and a cheap model for bulk tasks.

Where Danube Labs fits

If you need to choose and test models for a business workflow, we build small evaluation sets so the choice rests on your own data. See our free intro call.