I agree with amastropolo, basically what one you think looks the best, as race doesn't play as crucial of a role as it used to. However my personal cleric looks pretty sporty wearing a robe (he mainly hangs out in the lobby any way so doesnt need his armor on at all times). If you are a humanoid race
Shade Silk Robe is fairly easy to craft at low levels. Granted its actually a
tunic, but has a robe appearance on most races.