Vampire The Masquerade VtM 2nd Edition oWOD
The mix varies, but I still play VtM, and I see more ads for VtM games than I do for VtR games. The other lines are more mixed. Werewolf and Mage seem to be about even, maybe slightly slanted toward nWoD. Both incarnations of Changeling are rare, but CtL is, I think, generally the more common.
Main differences? The system has been streamlined quite a bit. The game has been set-up with the assumption that there's no canon metaplot, Vampire politics has been re-scaled to be mostly city-wide. International politics isn't as much of a thing.