An opinionated guide to which AI to use to do stuff
Simon Willison Simon Willison ● Covered by 4 sources
Ethan Mollick's guide to choosing AI tools has shifted focus from chat models like ChatGPT and Claude toward agentic systems capable of performing hours of human work autonomously. The most powerful implementations give AI access to your computer through desktop apps using modes like ChatGPT's Codex and Claude's Cowork, which enable broader capabilities than browser-based versions. As agentic AI matures, the choice of tool increasingly depends on whether users need simple conversation or autonomous work completion, with naming conventions across platforms remaining confusing.
Why it matters
An opinionated guide to which AI to use to do stuff It's interesting watching the evolution of Ethan Mollick's guide over time. A year ago it was still all about chat - ChatGPT, Claude, Gemini - with o3, Claude 4 Opus, and Gemini 2.5 Pro as the models and Deep Research as a useful alternative mode. Today it's much more about agentic systems - "where the AI is capable of doing the equivalent of many hours of real human work in one go". Gemini has fallen off Ethan's list, since Google still doesn’t have an established entry in the Codex/ChatGPT Work/Cowork category. Gemini Spark has yet to prove itself! Ethan offers a useful explanation of the ways you can give ChatGPT or Claude a computer to use: To use the computers provided by the AI companies, the mode you want is called ChatGPT Work in ChatGPT, and Cowork in Claude (the naming will not get less confusing, I am sorry to say). [...] The most powerful way to use AI is to give it access to your computer. You do that by downloading the C
