Here are some systems I've had a lot of fun playing: Chaosphere (Hunger Games), 10 player FFA: Endor, FFA or team games: Ice is Melting, FFA or team games: Lava boss, FFA or team games: Race for the Stars v2, 10 player FFA:
Three more maps: Chaossphere 3, 10 player FFA: Rocky Mountains, 10 player FFA or 5v5: Damnation System, FFA or team play: