Whatever system you use, people are going to try to engage in whatever behaviors the system allows that contributes to improving their stats.

You can change the system. E.g. I suggested respawning at the same HP upon suicide to discourage people from suiciding in an anti-social fit when they're at a certain AP threshold. I suppose you could respawn people in different places if they die in a mob (maybe a very large morgue where the staff are freaking out about a zombie apocalypse?)

You can also change the stats and players behaviors will start optimizing for the new stat instead of the old one. E.g. if you factor in deaths as a negative, people will try to minimize their deaths while maximizing their kills instead of simply trying to maximize their kills.

So change the oh-so-holy system or change the oh-so-holy stats.