Well, here is a thing.
Voodoo and Voodoo 2 DO NEED a 2D card because they only have 3dfx chipset. Your choice might be Banshee, because it's the firsth 3dfx card that has a 2D functions, and has a pretty good 2D performance.
So that is the firsth big difference between Voodoo, Voodoo 2 and Banshee. Second one is that Banshe doesnt support multi-texture so Voodoo 2 will still do a better job in 3D with games which do support multi-texture. So I think you should go with Banshee card and spend around $150 for Diamond Banshee.