If your cockerels are of certain breeds, not mixes, then google those breed clubs. They will show 'ideal' conformation for their breed, which is helpful.
Avoid obvious conformation faults, as mentioned above. Wry tail is a big one, because it's abnormal pelvic conformation, not only about looks. Likewise any issues with the beak.
I also agree that the 'friendly' cockerels are being bold, and sizing you up, and may be less likely to turn out well.
And, I have zero tolerance for human aggression! A good rooster is busy looking for actual predators, treating his hens, and while he knows where you are, doesn't see you as a flock member to dominate, but as a separate species; the giant who brings food!
Your less dominant cockerels may change if the two bigger ones leave, who knows?
I don't hand feed or handle my cockerels, only pick them up if absolutely necessary. They aren't pets, they have work to do.
Mary