Public ranking. Every public match counts: 1v1 duels, 2v2 relays (each team member gets the win or the loss) and battles. Private rooms are invite-only and don't count. Sorted by matches won; best streak breaks ties.
Fair play: against the same rival, at most 3 wins a day count, and if someone leaves in the first 15 seconds without any kill, the match doesn't count.