Lockdown "Rooms" for friends only, option to invite players
4-8 player "Last Man Standing" mode with lockdown classes, basically TDM
Permanent global rankings based on win/loss ratio, damage, caps, and defends. The ranking system would be based off of the MVP calculator used by the NBA which basically adds every statistic and divides them.
EDIT: You probably should keep the original ranking system and just place the one I suggested under a different tab or something, maybe add a search bar to look up specific players
PvP no matter how you look at it, is pretty much endgame material for anyone that clears the content you give them. Please consider making these changes.
I must warn you. Making permanent statistics is a terrible idea. The more you promote them the more you promote bad behaviour, hacking, exploiting and statpadding. No permanent stats, if you want egoboost via KDR you are playing the wrong game anyways. It could show just kills, wins but no deaths and losses. You can have all the fun stats but without the cons