I like Nightwing's Pre-New 52 costume where he had blue instead of red. I always loved all of the Robin costumes even the original. I love Wonder Woman's New 52 look where she has silver instead of gold.
Tim's Red Robin costume was badass. I also have to give a shout out to Booster Gold's pre-New 52 costume as well, not too shabby for a costume composed of a bunch of stolen s###. Also, Batman's Batman Inc. suit was great.