Part of Schumacher's greatness is his ability to get the best team then get the best from them. You wouldn't have a team like Ferrari pumping millions into their car if they had Irvine as the number 1 driver.
Fact is Schumacher's ability in a Jordan then in a Benetton alerted Ferrari to his ability.
Villeneuve was given the chance at BAR to do what MS did at Ferrari. Bring in his own team, have a blank cheque, yet he did nothing of note. Toyota now have the biggest budget in F1 and they've yet to win a race.
We can all say he got the best opportunity to win, but the fact remains that these opportunties only present themselves to the best people, and he took that oportunity and realised it, in a way that no-one before him ever has. And others had the same chance and let it go begging.
He is one of the best, and no-one can take that from him. But he still lags behind the likes of G.Villeneuve, Rosemeyer, Senna and the definite number 1 Tazio Nuvolari as the greatest ever.