If modern drivers can do a few races, much less entire seasons without all the telemetric data or what amounts to lap-wide spotters b/c of all the tv cameras than maybe I'll consider the likes of Hamilton in the best ever category. But in an era when the cars rarely break down, there's mountains of computer data to help, not for me. Everybody who came after the mid-90s are notched down for me no matter how good they are b/c things got sanitized, over policed, and the computers began to take out all the guess work & even crap cars got at least fairly reliable following that period.
On pure talent of what I've seen in my life, Senna, Prost & Lauda are the best I've ever seen. And from how my dad used to talk about drivers you could add Stewart & Clark & maybe Andretti, since Mario drove & won in just about everything except rally cars.