Really, the real incentive is just to have fun and still do your best so you don't screw alliance over if they're trying to get a win.
I'm not a PvP type player honestly, I like to PVP just to get a break from boring old PvE that is run over and over. And boss rotations are the same every match so it's not really that fun once you know the fight already.
PvP always feel different every round, and it really gets me into all the fighting too. To sum it up "PvP is exciting!"
