I think the comparison is an apples/oranges things at best. I think that Jack has more acting range, generally speaking and that Will is a trained comedian, which informs his choices as an actor. Jack does have a zany side, but he's also done very straight acting roles like in "King Kong". Jack's musical side is a big influence as well. Will is every bit the comedian in the roles he chooses and is much more physical in his comedy. Don't get me wrong, he's a great actor as well, but most often the roles are extensions of the guy we got to know at SNL.