A large fowl rooster can be a good alerter to the hens. He generally won't lock in battle with a hawk. If he does, often he loses giving his life for his hens....or not.
My Barnevelder boy is very good to keep a watch and call the girls in away from trouble. He also has stood by in a oorner as a hawk devoured one of his bantam girls....but he screamed his disapproval at him. (He also screamed disapproval when a coon ate several girls in the coop...he did try to run interference, but basically is a coward at heart). But he is a sweet heart with a gentle nature, which I like as he alerts and doesn't attack me or other animals. Since I'm hatching his chicks, I want good temperament.
And yes, a large rooster will breed your bantams. If they are very small he could hurt them. Getting him a hen his size and letting him free range with the full flock will not stop him from trying to mate the small bantams.
My Barnevelder boy is pretty big, and he has mated with my bantam Cochins to no ill effect. I'm a little more worried about my current Silkie. She is very tiny and I think he might hurt her. A Sebright is very small.
Of your choices....I'd take the Ameraucana (which is likely an Easter Egger) as you could get some green egg laying hens out of him if you hatch eggs fertilized by him. Easter Eggers are generally nice birds, and overall, I've heard good reports from those that have them.
Of the three, I would not take the RIR rooster. They tend to get pretty aggressive. He might be excellent at fighting hawks, but he may also be rough on your girls and a general nuisance to man and beast alike.
I'm not familiar enough with the Bielefelder to know temperament. That would be a very rare breed and honestly quite valuable if he really is one. Sheer value wise, he might be nice to have on the property, but I'd definitely get hens for him as that would become a valuable line.
So bottom line...don't expect a large rooster to actually do battle and win with hawks. He may, or he may not, or he may and you need a new rooster.
The best thing is to string up some hawk netting at strategic locations and provide "bomb shelters" for the birds when a hawk flies by. The alert from the rooster and a quick dive into cover helps as well.
LofMc