One of the most important ways to ensure a harmonious flock is making sure that your hen/rooster ratio is reasonable. Multiple roosters will squabble and even kill each other when competing for too few hen’s affections. Many towns have ordinances against roosters because of their before-dawn crowing, and it’s always a good idea to check with your neighbors even if your town doesn’t have any specific laws.
Having said that, a couple of roosters bring a lot of entertainment and personality to a flock. They are usually more friendly than hens because they are not afraid, and their clucking and presenting for hens is endlessly amusing.