Generally whatās Iāve seen personally is males with more hollow stems seem to have faster growth rate, also tend to really dump pollen and early. But when it boils down to it the best way to see if a male is really worthy is to test out the progeny. Thatās why breeding takes so much time, effort and space to keep the male around see how it crosses to other cultivars.
Iām actually just as fond of male plants these days as I am females lol