We select for good temperament first, no human aggression, not nasty to flockmates. No physical defects, equally important. Then correct structure and type for the breed, according to the SOP. If you aren't selecting for show, more flexability there if necessary.
Removing cockerels is a gradual process; obvious losers go first, then watch the possibles over more time, and get down to maybe two really nice ones.
This year we had five cockerels, and recently sent three of them, all nice, but not as nice as the keepers, to a local auction, where they were bought by people who liked them for their flocks. Nasty boys go to the freezer, not resale as flock members!
Mary