When I first followed the sport, it was 1987, and I was a Prost fan. He wasn't leading the race, but was charging. In the end, his car stopped with 2 laps to go. He never gave up, even though his McLaren had engine and alternator belt issues all year long. So I was lucky to not get on the bandwagon and appreciate his drivng...
However, Nigel Mansell really drove the car at 110%, especailly when the car only set up 80% of the way. Great performeances from him until mid-1990. After that, he really stopped trying, save a few times in '91 (Italy, Spain, Brazil). By then, his attitude just seemed to be that he deserved the best car, and if he didn't get it, it wasn't worth racing.
Senna was great to watch, but his ideas about driving ethics was about as dirty as it gets. I could respect that he was the fastest driver 90% of the time, but I disliked his cry-baby tactics. By 1992, he'd matured a lot, and it was fun watching him again.
Jean Alesi was always fun to watch. He never had the best car, and sometimes had only half-decent machinery to deal with. But you were usually going to get a good race out of him. Alesi was one of the few drivers that RACED a Grand Prix car, whether for the lead or for 12th place. F1's not the same without him.
As for the past few years, only Alonso, Klien, and Massa keep on trying to make a race of the sport. Sometimes a few others give it a go, because that's why we watch it.