o3/o3-pro is probably the best model, or very close to being the best model, overall. It beats Grok 4 in writing/composition and analysis tasks. [1] Performance is a toss-up between o3 and Claude 4 Opus, but I find o3 easier to interact with and more trustworthy. (Less likely to push back against requests and more likely to attempt to fulfill them in good faith.)
4.5 is also great for certain things. Of all models, it's the second best writer. (DeepSeek R1 is the best prose stylist, surprisingly!)
[1] - This is Grok 4: https://x.com/i/grok/share/e51O9rK0W7UaIN81nFBQoJDSs
This is o3-pro, same question: https://chatgpt.com/s/t_68710185cf04819185dc25233280e46b
o3 made fewer mistakes and drafted a more neatly structured and better written output.