The black ball for me is a lot smother..... I haven't had near as many troubles with the black trackball sticking as much as any other color.... not sure why..... maybe I just got a really good one, or I tend to wash my hands more..... I would go black!!
I love my black trackball. The color goes with everything and it doesn't show dirt as much as white or any other color. The only bad thing is it doesn't glow.
Posted from my CrackBerry at wapforums.crackberry.com