I hear a lot of people talk about gaming burnout on boards like this one and, from my point of view, a lot of it seems to come from people who have invested a lot of effort into one game. I suggest you branch out for a while, and I don't mean just other RP systems like you say you've tried.
Get a few board or card games like Chez Geek, Munchkin, Carcassone, EuroRails, Formula DE. Play them for a while while drinking beer and eating pretzels. Do some other low-key get togethers with your friends. Watch movies together.
Sooner or later, you'll get a little distance on it, relax, and get your groove back.