I'm probably in the minority here, but I find the Lego games to be some of the worst co-op experiences out there. It's an exercise in patience and nonsense with long-ass boring levels with little to no variety. My wife and I tried a nice little bout on Lego Star Wars and we were yelling and swearing at each other within ten minutes.
That being said, I think there are a ton of arcade games that are really good like Bomberman, Schizoid, Robotron, Castle Crashers, and my favorite of all Geometry Wars 2.