VLC for almost everything
Occasionally I end up using Real alternative (because I won't install the P.O.S. "Real" software...which is essenially ad-ware) and I keep WMP installed because of the NFL sunday ticket since their online service for watching the games works from WMP only!...which sucks but I get by.
I try to avoid having to use quicktime if possible but I don't loath it nearly as much as I do WMP and Real.