I don't think I ever suggested not to look good/professional or not to do something that makes you feel confident. I just really think people are overthinking it. If it is a personal thing, then do whatever works for you. If the opinion of a random stranger on SDN will give you the confidence to do well, fine. If the only color combination that makes you perform well is a navy suit vs a black suit and a tie with a love note from your high school girlfriend written in silver Sharpie on the back, fine. But people were asking other people what to wear which makes me think it has nothing to do about what feels good to them. And when it comes down to it, I HIGHLY doubt that the admissions committee will favor someone based off of suit color.