My vote is pretty much anything goes. I'm up for Pathfinder, 4e, 5e, or even White Werewolf stuff.
I'm only comfortable DMing if we do 4e or 5e though. I haven't messed with Werewolf's stuff enough to have any real idea of what I'm doing and I haven't touched Pathfinder since 4e really got going.
Since we're discussing concepts, I wouldn't mind trying my hand at the Holy Gun Paladin, Human of course. If we do Pathfinder.