I made a similar suggestion with map pools based on play style, see this thread: Suggestion for ranked multiplayer ELO system
If unranked play is the way to go to play on the exact map and settings you like and creating balanced games is the main concern, then I would suggest to somehow incorporate a rating so that fair teams can be made. The ranked elo could be shown here, or else some unofficial rank or win statistics so that players have enough information to create teams. Of course the ranked play will by design always give more balanced teams than unranked play, there’s no way around that.