I think they have a better agent personality which pushes back and isn't sycophantic. It has been awhile since I've used the others but that's where it locked me in and I've stuck with it.
Not sure about that one... But I think the true secret sauce for all these models is how they reason. GPT never outputs how it thinks, which "saves on tokens" but Claude absolutely tells you how it thinks, and there's people who use how it reasons about solving problems to finetune smaller open source models, with surprisingly better output.
I have got so use to the Claude personality / style of conversation that I really can't be bothered to try these other models anymore. They need to take a huge jump but that seems to be getting harder and harder because of the jumps Anthropic makes.
This Grok version is a joke if it is not even clearing the bar now. I am just getting use to and using Fable more and more. I am also trying not to forget that this is the highly delayed old Fable model that Grok can't even beat on release. There will be a new version that expands the lead in a week or two.
It all harder and harder to judge too. I just had a prompt/response this morning that Fable finally displayed its intelligence and vowed me. That is partly because anything with even the vaguest reference to biology defaults back to Opus.