If your sail has colors in it, you might want to try to match the tramp to one of those -- so you can be a well-coordinated kind of guy.

Black absorbs heat, so you might not want it if you are sailing in a hot, light-air place. If you are sailing someplace chilly, black might be good.

I like the teal and the turquoise, because they have a tropical look that makes you feel like you are sailing in the Caribbean even if you are on a lake in Kansas. And colors look more fun and friendly if you are going to invite women aboard.