In terms of roosters, which breed has given you the most success?

[Cluckwork Orange]

Beautiful
Agreed
Are the hens in the pic Cochins or Rocks?

mostly production rocks. there's a cochin and a splash ameraucana in the middle.

edit for spelling

 

[MROO]

The main thing to remember here is that a rooster is NOT a flock protector - he is a danger-alert alarm. If you want to protect your parents' chickens from predators, either seriously upgrade their man-made protections (and keep the birds inside an enclosed run) or get a 24/7 livestock protection dog (LGD.) The "fight-to-the-death-to-protect-his- ladies" stories are rare - and generally one-offs, as the rooster is then dead and you have to start over again!
That doesn't mean that your parents shouldn't keep a rooster. There are a lot of friendly ones available (check the rehoming forum.) "The Boys" are an excellent early warning system and can definitely save lives. I love having my fellows around - not just for the morning wake-up calls, but for the eye candy bonus, as well!

 

[Emmaloveschickens9156]

Plymouth Rock, but you have to have the right amount of hens, and they have to be the right size for your roo to mate with.