I don't know if it is the greates win of all times, but the race that immediately popped up in my mind was Schumachers first win for Ferrari in a very, very wet Barcelona 1996. After a 3th in qualifying and a poor start he drove into the first corner in the midfield. But after that, he passed his competitors 1 by 1, and in lap 13 passed Villeneuve for the lead. He won the race with 3/4 minute ahead of Villeneuve and Alesi, and at least a lap of the other few drivers that were able to keep their car on the track. Among those who couldn't, the man who would in that year become world champion Damon Hill. Het spun 3 times, and the last time his car crashed into a wall.
In the same league is the GP of Europe in 1993 that Ayrton Senna won. He was 5th after the first corner, but only needed 1 lap of a wet Donnington Park to take the lead. He was the mastering the very changeble conditions better then anyone. He still needed no less than 4 pitstops to change from raintyres to slicks and vice versa, but archrivel Alain Prost pitted a record 7 times. In the end only Damon Hill managed to just stay on the lead lap.
