I guess it's more about texture than color really. I like stuff that's fuzzy like fleece or velvet. Lace is abrasive. Loose fitting sweats are good for easy access. You can fondle her butt and be able to get your hand out when her parents are close (this was when I was younger).
i'm not sure I have a favorite colour , but often pink can be really hot , red as well can be a strong colour . black can also be hot , especially for pants as it makes her butt hotter and smaller .
so a girl wearing a bright coloured top and black pants be a turn on to me