Prefer dry rubs. Something as simple as sea salt,pepper garlic and onion powder. Montreal Seasoning is ok. Use a rub on ribs and pork butts that is real good as well, has brown sugar, cayenne, cinnamon and a few other things in it...
If you haven't tried any of Steve Raichlen's books, try "How to Grill" or "BBQ USA" as a starter - it will seriously up your grilling/smoking/bbqing game!