White is the easiest color to maintain. It does not fade like colors do or show scratches as easily. The problem with black is not so much keeping it clean, but keeping it looking good. It shows EVERYTHING, from swirls and scratches to stone chips and we all know how thin, cheap Subaru paint is. Silver is the easiest to keep or at least look clean from far away. Silver is nice because of the lightness of the color and the metallic flakes help with reflection to make it look clean most of the time from far away. The first car I ever owned was silver. I used to keep it waxed pretty good and most of the time, just rinsing it at a DIY car wash was enough to make it look good. I went from a silver car to a black one, talk about night and day. I am still not 100% sure I am going with a white STi, but since this will be my daily driver I think white will be the easiest to keep looking good especially if I park it outside all day at work. I try to picture in my head a white STi with 18" anthracite OZs on it and some light tint on the windows, that is what I am thinking of. After owning 2 black Supras, one daily driven then sold to get a garage queen, I have come to the conclusion that anytime you wipe something on/off the finish it scratches. The more you wash it the worse it will get. A good rule of thumb is the darker the color the harder it will be to keep looking good. WRB will not be as bad as black becuase it is a metallic color. If you are not careful it can still show swirls though. I am pretty meticulous when it comes to my vehicles. Keeping them clean and looking good is a priority. I don't care if it is a beater I try to keep it clean. Shit, my cars are cleaner then my apartment.

Think about this, you are driving an STi. It is a damn nice car and will prolly draw attention, so you are going to want to keep it clean and wash it a lot. You might want to take that into consideration when choosing a color. Also how are you going to be washing it... by hand yourself or a drive though place, which is the worst way to do it. I live in an apartment and can not always wash the car how I like. Also during the winters here in Chicago it can get damn cold in February where I will only be able to go to the drive throughs. During the warmer days I usually mix up a bucket of water and soap and go to a DIY car wash at night when no one is there and wash the car myself, but when it's -10 out I can't do that. Oh yeah one of the first things I will be doing no matter what color I get, will be to get one of those clear stone guards applied to the front of the car.
Yeah the color is a tough choice. It's not like it's a shirt or something you don't have to wear all the time. It's like the color yellow. I see some cars I like it on but when I think about owning a yellow car myself, I can't imagine driving it everyday. It's not like I can turn it off or anything. It would be nice to have a sort of color changing paint, where you could change the color whenever you want.