Hmmm, tough to say. But I'm leaning towards the X-Men. JLU is so terribly weakened (I mean Flash couldn't even catch up to a speeding truck, Superman is constantly being thrown around like a rag doll). Then again, Rogue is powerless except for her absorbing abilities, and Iceman and Jean are not at their fullest potential (or should we assume Jean is Phoenix now?). Still, I bet Cyclops could actually HURT Superman from the cartoon, and with MM showing such limited phsycic ability, Prof. X could probably do a number on him and the rest of the team without much difficulty.