I've had both black on my previous cars (s13 240sx, and Audi B5 A4) and white on my current car (E46 M3) and though I love the white, when clean and taken care of properly, nothing beats a nice, black paint job.
I use to wash my s13 3 times a week, minimum, but it was a spray off at a local car wash with the pressure washer, not touching the paint what so ever with any sponges, mitts, etc.
Once every two weeks, i'd set aside a day to wash and wax the car. I'd use the 2 bucket solution, which you would be suprised the difference that alone makes. Afterwards, I'd bust out the Porter Cable and wax the complete car with McGuires Show finish high gloss wax. Twice during the summer, I would do a full 3 step system, Once at the beginning of the year (April/May) and again around the end of July/August. That would be a complete strip of the old wax, use some 3m fine cut compound to take out any swirls, then seal it with some 3m polish (Hand glaze I think it's called), then a coat of Mothers pure carnuba wax afterwards.
Doing that, really gave the black what it deserves. The white on my M3, although it's very fresh looking, and doesn't require much maintaining, a spray off here and there makes it look good, it doesn't have the same appeal as the black, although with the M3, I feel the white looks best on it being more of a sport/luxury car.
If I do decide to buy a gen coupe, it will be black, because when it comes to a 2 door sports car, nothing will beat a nice show, black finish, especially showing off the gen coupe's curvy body lines. You just have to know how to take care of the finish.