Hm... last I checked, Rakion and Wolfteam. The latter is popular on Aeria Games but... the cash shop unbalances it so much, and its only like S4/Gunz in Wolf mode.
Don't know too much about Rakion, but Wolf Team is interesting in that you can play it like a classic FPS or you can play in Third Person as a Wolf, there are quite a few interesting modes, from Death match to the more interesting Bomb S2, where the humans must plan a bomb and the wolves have to stop them by killing them all or defusing the planted bomb. Only issue with it would be that the items humans can buy in the CS are crazy...I mean CRAZY over powered, Golden guns that shred wolves to bits in less than seconds, armor that makes them take far more claw hits than they should (A human without it only survives 2-3 Claw hits from most wolves, but only 1 from some and 4-6 of others, each with their own ups and downs, of course) and knife upgrades that make their knives nearly as strong as wolves claws
If you can handle the CS imbalances then I'd say go for Wolf Team, its still a fun game, its been a while too so perhaps they've weakened some of the items in the CS.