very good inquiry.
i am eering on side of early F1 and going with José Froilán González, possibly Fangio - great rivalry but Gonzalez really lost out big in-spite of immense talent.
But we can go down the eras here, in the cigar car days it has to be Graham Hill, he was just glorious.
Early wing cars i would choose Jackie Stewart - that is how you drive in my opinion.
70s was very much time i would have been fan of Clay Regazzoni, rené Arnoux towards end of that decade
This leads to the 80s and Elio de Angelis, Andrea de Cessaris (okay this is just because he was exceptionaly entertaining to watch),
In 90s you have your Damon Hill, Mika Hakkinen, both suffered because of certain somone i will not even give space to name.
Early millennium had undeniably one of most painful talented drivers, unable to win title in Juanpablo Montoya, i also conssider likes of Giancarlo Fisichella to be man in wrong cars at wrong time, otherwise he would have been capible of winnig title.
i kinda gave up on F1 after the string of buyouts / bancruptcies of:
It just felt like there is no one to care about, cars looked hideous and point system was broken.