MattW Services
I won't post the link in case he doesn't want me to, but get in touch with him on xenforo.com - he's always come highly recommended. I've had a history of bad hosts where XenForo is concerned, so I decided to start investing properly and I'm glad I did.. He took care of the migration which was seamless, and there hasn't really been a blip to speak of.
I guess the only downside is that you have less control than you do with other hosts and shared hosting, but perhaps that's a good thing if it's more stable! I had an issue where a desired addon required a PHP module to be installed - Matt took care of this within 24 hours. He goes above and beyond.