FFA would be the most fun, but it's also the one that's nearly impossible to manage, since you really can't stop people from brocoding in some shape or form. In the first ffa I just ran from all fights knowing it would be better to avoid them early on. People can use this excuse to avoid fighting their friends. People can also decide who to assist during a large group fight, coming together to take down a stronger foe and any who joined them and then fighting each other afterwards.