Hands down I find Co-operation to be the most fun, most fulfilling. You see in competition everything has to be as fair and as Balanced as possible. Which is a virtual impossibility to begin with. Though games can get close. So it's always a question of if the other players were actually good, got lucky or happen to pick the counter to your strategy. In co-op you can throw fair right out the window. Crank things up to ridiculous OP levels and tell the players "good luck". If you find an exploit, cheat or OP AF weapon... well good on yah. It's not likely the A.I. was playing fair and your helping your team rather then ruining the sportsmanship of a competition. Ya Co-op is where it's at.