My experience is as follows:

- "Reason" toggle just got enabled for me as a free tier user of ChatGPT's webchat. Apparently this is o3-mini - I have Copilot Pro (offered to me for free), which apparently has o1 too (as well as Sonnet, etc.)

From my experience DeepSeek R1 (webchat) is more expressive, more creative and its writing style is leagues better than OpenAI's models, however it under-performs Sonnet when changing code ("code completion").

Comparison screenshots for prompt "In C++, is a reference to "const C" a "const reference to C"?": https://imgur.com/a/c-is-reference-to-const-c-const-referenc...

tl;dr keep using Claude for code and DeepSeek webchat for technical questions