Hi guys new to the forum, but i think im still allowed a bit of input.
From past experience, i wouldnt recommend ufgl or clanbase for leagues. By far the best is enemy down which has, 1v1, 2v2, 3v3, 4v4, 5v5 ladders leagues and cups

Its ran very well, they have a few must haves like you must have a decent website displaying allsorts, a mirc channel etc. You get to decline matches also (so if a really good clan challenges you ya can run away like wimps

)