Highlander
Highlander, also referred to as 9v9, is a large part of the competitive community and where many new players start in, as it requires 1 of each class. There are several competitive leagues that have a 9v9 division, spanning several countries.
Leagues
(American)
(European) ETF2L- http://etf2l.org/
(Australia) OzFortress- http://ozfortress.com/ ATF2L- http://www.atf2l.org
(Multinational) UGC- http://www.ugcleague.com IGL- http://www.playigl.com/ CEVO- http://www.cevo.com/