Seeing how ELO is the best ranking system so far*, I'd rather not get rid of it.

Instead I'd add ELO decay, meaning that if you are inactive (=don't play games) for X ammount of time you start slowly losing your ELO.

Also, I'd remake the ranking system, so that you wouldn't gain GLOBAL rank when playing in player made rooms. You would still gain mod rank, because there are just too many mods in this game.

I'd add "ranked" servers, which would replace the (always so empty) official Black Belt and Ultimate rooms. Preferably with some kind of (automated) mod rotation.

That would help with "Rank farming", and somewhat standardize speed you gain ELO/wins.

*It is. Just not well suited to a game as diverse as Toribash is.

Imo biggest problem with QI ranking is the fact that you can actually BUY Qi.
Also, farming Qi is even simpler than farming ELO. You don't even have to win.