What is your weight? What are your roads like? How stout are the rims?
Im about 170. On a vintage racing tubular rim I prefer a 32 hole, with the rear rim being a bit more stout. I have a set of 28h wheels that I use on good roads. I try to stick with rims I know, when building a set. I like GP4 Mavic for my rear wheel & Mavic GL330 for the front. My Merckx is built up with Ambrosio Crono 36 hole rims. It more of an every day bike. These rims are really smooth. Wish I had a set in 32h.