Which AI model should I use? October 2026

Which AI model should I use?

As of 11 October 2026, use Claude Opus 5.5 for writing and coding, ChatGPT for research where you need sources, and any current model for everyday questions, free ones included. The table below gives the evidence for each pick.

These picks will change within weeks. Between 1 September and 7 October 2026, OpenAI, Anthropic and Google released ten new models between them. I use AI heavily and pay for a frontier plan for important work, but for most people the better move is a good default they never have to maintain.

The best AI model for each job (11 October 2026)

Sources: LMArena (arena.ai) text, creative-writing and WebDev boards, updated 8 October 2026; LMArena Search board, updated 24 August 2026; Artificial Analysis Intelligence Index v4.3.2, read 11 October 2026; Claude's pricing page and OpenAI's ChatGPT plans, October 2026.

LMArena scores come from blind votes. People type their own prompt, see two anonymous answers and choose the better one. The gaps are smaller than they look: a 32-point lead means the higher model wins about 55 votes in 100. Artificial Analysis combines a set of standard tests in reasoning, knowledge, math and coding, so it shows more clearly where the most expensive models pull ahead.

The research row is the least certain. The Search board hasn't updated since GPT-6 and Claude Opus 5.5 launched on 22 September. Perplexity is the specialist here. I had a free year of Perplexity Pro through my phone company, used it heavily for a few weeks, then didn't open it for the remaining ten months, and was glad I hadn't paid. My impression, and it is only an impression, was that its answers felt weaker than the same models used directly. The full comparison is in Plainly vs Perplexity.

Is there one best AI model?

No. Each leaderboard crowns a different model, and the overall leader keeps moving. Google's Gemini 4 Argon, announced on 30 September, now leads LMArena's text board (1525, marked preliminary), but most people can't use it yet: Google's DeepMind site says the company is "strengthening frontier safeguards before broad availability". Claude Opus 5.5 leads on code and on the Artificial Analysis index. An OpenAI model led the last search ranking.

My own experience matches the split. Claude writes best, ChatGPT is strongest on logic, and Gemini is good at pulling together information from many sources.

Below the top spot, the gaps on everyday work are small and the price gaps are large. On LMArena's chat votes, Kimi K3 sits 19 points behind Opus 5.5. On harder tests the gap is real: the best open model scores 46 on the Artificial Analysis index against 58 for Opus 5.5. The price gap is far larger. On OpenRouter on 11 October 2026, Claude Opus 5.5 costs about 17 times as much per output token as DeepSeek V4.1 Flash. The reasons Chinese labs can charge so little are in why Chinese AI models cost less.

How often the best model changes

Five weeks of notable releases, from Artificial Analysis's model list:

Four of the models in the first table came out in these five weeks. Choosing well by hand means reading release notes from half a dozen labs and re-testing your own tasks after each one. I test new models constantly, and staying current still takes near-daily attention and some technical skill.

What I use: Claude for important work, cheap open models for the rest

I split my AI use in two. Important tasks go to Claude. I pay for Claude Max 5× at US$100 a month and still hit its usage limit. Until around January 2026 I was on Claude Pro, billed at US$22 a month, and my friends and I always ran out on it. More on how those limits work is in Claude Pro usage limits.

Everyday life and side projects go to cheap Chinese open-source models. I reach them through Hermes, a desktop chat app I run with my own OpenRouter key, which is a tool for technical people. In the month to 15 September 2026 I spent about US$49 on OpenRouter. The two everyday chat models, DeepSeek V4 Flash and GLM 5.3 Flash, came to $18.90 of it. Kimi K3 ($4.80) and Gemini 3.7 Flash ($1.93) took smaller amounts, and about $6 went on image generation. I also have ChatGPT Go, which comes with my Revolut subscription.

The cheap models hold up on ordinary writing. On 2 September 2026 I gave ChatGPT Go, Plainly and Claude Fable 5 the same five short writing tasks. ChatGPT and Plainly each scored 61 of 75 and Fable 5 scored 59. The order wasn't randomized, so treat it as one person's read; the outputs are in the writing test.

Why most people shouldn't copy my setup

Running two kinds of AI saves money, and it brings two problems.

1. The cheap half needs constant attention. The best cheap model changes every few weeks, as the release table shows, and staying on a good one means tracking releases yourself.
2. The cheap models had no good consumer interface. The open-model labs build for technical users. When I went looking for a clean site to hand a non-technical friend, there wasn't one. The usual route is API keys, prepaid credits and a model menu, which the API route covers.

For most people, dual-wielding is a hobbyist's answer to a problem an app should solve. If you code, if your work pays for AI, or if you use it professionally, a frontier plan earns its price. Everyone else is better served by one default that someone else keeps current.

Why are there so many AI apps?

Because the app is the easy part. A lab trains the model; an app is a screen that sends your question to one. OpenRouter, a service that sells access to models from many labs, listed about 350 models from more than 50 makers on 11 October 2026, and any developer can put a chat window on any of them. Many AI apps are built this way, Plainly included.

The labs also pull in two directions. The US labs (OpenAI, Anthropic, Google) compete on maximum capability. The Chinese labs (DeepSeek, Alibaba, Moonshot, Z.ai, Xiaomi) compete on efficiency and publish open weights that anyone can host. Both strategies produce a steady stream of releases. Expecting an ordinary person to track all of that wastes their time.

What to do instead: pick a default you don't maintain

My rule of thumb, by how much you use AI:

• A little: the $20 Claude plan.
• A lot: a $5 app like Plainly, because a $20 plan's usage limit is what heavy users hit first.
• A huge amount: the $100 Claude Max or ChatGPT Pro plan.

Plainly, the middle option, is the app I built. Plainly runs one capable open-source model and switches when a better one comes out. You never pick. It costs $5 a month. It can take the place of the cheap half of a dual-wield. It does not replace a frontier plan: for important work I still pay Anthropic, and if your work needs the top of the first table, you should pay for one too.

On any given day, a default won't be the model at the top of the leaderboard. On everyday questions the votes say you would rarely notice the difference; on hard code and long reasoning you would.