I really want a cremello. Or a perlino. I don't know why, but I really do.
Out of the "plain" colours my favourite is definitely bay. I like pale palominos, buckskins, bay and black duns.
I like mares. I doubt I would buy a non-mare, unless I really liked them. There is a stallion I've been riding a little, and in the future, if I had money and he was for sale, I'd think of buying him (but then probably geld).
I like stars that are well defined and shaped. I like stripes or blazes that aren't too large or regular. Not a huge fan of white feet.
Do not like chestnuts. Except for dark liver chestnuts, like them a lot.
Would go for a paint in any colour but chestnut (or greying). Will not buy a grey, they get so dirty, and I've known some to have cancer issues.