Wish I could help, but I'm in the same boat really. I'd love to find a successor to VTMB, but there's just nothing out there that quite fits the bill. And maybe there never will be.
The closest thing I've found that gives me a similar level of enjoyment is Skyrim / Oblivion - you've got very similar RPG and character development options, along with quests and a variety of weapons, as well as 1st or 3rd person viewpoints.
A recent highlight was the Dawnguard expansion for Skyrim, actually focused very much on vampires and either killing them or helping them. Didn't really 'get' playing as the Vampire Lord though, maybe my mods had made it unbalanced to play as him - he just seemed really weak.