Last time I remember Vince being heel was when Punk did the Pipebomb thing and that was nothing compared to 90's Vince. Even if he were to turn heel now I doubt it would be successful because he just seems unmotivated to be out there anymore. Heyman on the other hand has been a great heel since his return, although he is a just a moving trophy case that occasionally speaks. So if we're basing it as of late then Heyman wins.
On the other hand if we're basing it overall, Vince can't be touched. Vince was THE top heel of the 90's, not Triple H. I think more people would rather see Vince in a match than him. Vince played it real good in the 90's, better than Heyman (who I would consider an anti-hero more than a heel because he did have a bit of fan support, and Bishoff who's just too mid 80's Miami for me.