I test a lot of them, online and with Ollama, and Sonnet 3.5 is in a league of its own for practical coding purposes.

Still makes a lot of mistakes, but it gets things "more right" than any of the others in a much more consistent basis.

I've now cancelled my ChatGPT subscription to Claude and also mostly stopped using the APIs (I use Msty to compare most models, you can give the same prompt to multiple models at once and compare the results).

Sonnet 3.5 is amazing.

Sonnet is the best at the moment. GPT-4o is within a margin of error in capability. Use both.

Isn't GPT-4, rather than GPT-4o the general best one? I am not talking about benchmarks, but the personal experience instead. GPT-4 always seem more understanding, says no where it should more often, corrects and identifies errors more often. 4o seems to go with the flow without much notice/inspection and keeps blabbering the way it does instead of following the conversation style.

Yup. I use 4o until it fails on something, pull in 4, then back to 4o. Rinse and repeat.

Is there an architectural reason Sonnet beats 4o? Or is it simply a matter of training corpus?

We don't know what exact architecture and optimizations both of those models use, it's all proprietary nowadays :)

I'm also using Sonnet to work on a library in Mojo and I've had pleasant experiences!