It's kinda hard to explain. I think most people have the most fun playing a game where their skill is near the same level. I'm a scrub and I always try and fight based on my gut instincts instead of concrete knowledge based on the specifics of a game's mechanics. Because of this I don't like really competitive players that much because playing a game with them is pretty rough, and playing online I tend to find very hardcore players that completely wreck me.

Basically, the competitive teams have the most fun playing with other competitive teams

Part of that is my fault though. I could learn the ins and outs of the game to improve myself but I tend to play games pretty casually. I just sit down, load up a video or TV show, and start playing a game at the same time