What if instead of having social and competitive playlist, each player has option on what types of players he or she wants to play with/against. Options would include ranked/social, region, talkers/quiet, team player/lonewolf. You could also allow yourself to join in progress for good games only if you are willing so matches with quitters will be slightly better. Maybe you could also set our favorite map/mode combination for the playlist to make voting better.
Tell me what you think of this idea and more option you would add to this system.