>>95811476
depends how you paint
Black works best for block painting or whatever it's called, like in >>95810119 and is far less time consuming, but you might need more than one layer of a colour. You can also do a white drybrush over it
I've painted in white and grey primer before as well and would say white is better than grey since you want the colours to really come out and be bright at this scale
pic related was painted grey with normal acrylics, but any new 10mm stuff I now paint is in white and using speedpaints, look way better imo