From a users perspective, I was never a fan of Xenforo. I can't speak toward admin in Xenforo. But I can nearly always tell when I'm using a Xenforo site. Such a basic user experience.
VBulletin is terrible - that I have more experience with and hated every moment of it.
I dunno, resurrecting all the functions and features we have now will take a huge amount of time. I know I worked for nearly 2 weeks on and off to get the EasyUO code highlighting working correctly. (if you look at the code highlighting on EasyUO, they never got it right - phpBB)
There's something to be said about once you get something up and running that it doesn't give you any headaches for years. Just say'in.