I propose a system similar to the way we rank maps, but for people.
Just an option to thumbs up or thumbs down an individual during a match with them (You can change your opinion, but you always can only vote on them once.)
Players with higher PR's are obviously friendlier, funner, nicer individuals.
You could further this by adding the option in the creation of maps to only allow players of a certain PR to join.
Only arguments I can see people making is the possibility of people being jerks and downrating you, well, they can only do it during a match and if they do, that's their opinion, if you're truly a good player, other's will uprate you. Even in the case of somebody using multiple accounts to downrate you, they can only have so many and you interact with a vastly larger number of people each day anyway, so it won't make that much of a difference.