In before three million Kimi votes.
If not the best ever, I’d say the best for a long while back would be Nigel Mansell. I’d pick him even over Damon Hill, my first F1 idol, simply because there was something a little more special about our Nige. Damon could pull performances from nowhere sometimes and was a lot like Button is today, but Nigel had more natural speed and there had quite a few breathtaking overtaking manoeuvres to his name. The guy could have been a 3-times champion easily and it’s a shame his only one had to come at the wheel of a ridiculously dominant car, which has provided fodder for his detractors ever since.
Going way back, I’d say John Surtees. Still the only man to have ever won both the F1 and Grand Prix Motorcycle (what we’d call MotoGP now). Jochen Rindt deserves a mention but we’d never know if his potential would have come through (he was going to retire a world champion anyway before he died)