The only non-white puzzles that I use for speed are megaminx, pyracrystal, 4x4, and 2x2, all of which are black. I have no problem switching between black and white on any puzzle though, but I have difficulty with colored cubes.
Green.
My 1st DIY is green and I get better times with it than my black DIY of the same type. Although this could be because of the amount of time I have used it for compared to my black. Nonetheless, I like the colours that are not normally seen...I like to be different.