I've owned an Ibis White Audi S3 for a couple of years now, and I'm still loving it.
My decision to choose white was based purely on seeing another white Audi (an A5) drive past me and think WOW! At the time I was the owner of a Deep Pearl Blue VW Golf R32, so blue was out of the question for me - as I had owned the blue R32 for over 3+ years.
I think black S3's look great as well - especially the 'Black Edition' version - but they only tend to stand out after they've just been cleaned, and living in England is a nightmare as we're not a particularly dry country!
White Audi's tend to stand out all year-round, come rain or shine!
Good luck with your decision pal, you're going to love it either way...