I think the best player overall is very difficult to answer and probably changes based on who’s been studying more recently/has made more improvements in their game etc. There are so many different skills under the umbrella that I think it would perhaps be more useful to break it down further like who is the best at making live poker reads (a category where Negreanu would surely rank very well), or who is the best at GTO math?
One really amazing aspect of poker is that having one skill that’s extraordinarily developed can help to fill weaker skills, such as live reads somewhat making up for (though almost never entirely imo) a lack of thorough knowledge of profitable calling ranges. In most games it seems like you just have to be great at a number of specific skills to have any chance at doing well, whereas in poker I think it’s more possible to have success with a “mixed bag” of skills—though of course it’s always best to be amazing at everything haha