IF I had enough money to buy and support another horse I would also avoid greys. I lucked out that my 2 greys did not develop melanoma, at least where I could see it.
I prefer bays, red bays especially. I also like brown horses, except they do tend to look a lot alike.
I never had a chestnut mare but I did own two chestnut geldings. Way back when a century or so ago I’ve read in books published then that said that ALL chestnut horses were super sensitive, almost exactly what people say chestnut TB mares are like in personality today.
Of course if I could afford a horse I would welcome a chestnut Arabian mare, well any type or color of Arabian. I would hesitate to say no Arab grey mares because that is what the Universe would send me if I got too dogmatic about it.
Hard pass for me? Kissing spine usually (that does depend on the horse), and the problems with the lower neck vertebrae (HARD no.)