Well I just wanted to know if RIRs are better than BCs since I might get one RIR rooster later on and I just wanted to know if I making the right choice
Each breed has a different characteristic... Rhode Island's may be mentioned in an article as docile and broody but you could have a nasty hen that pecks the babies.
All I'm trying to say is that handling behavior it is almost unmanageable. Personally though, I have had better luck with Cochin. (Not many folks talk highly of Rhode Island's).
Both breeds should be fertile. Large fowl Cochin roosters are bigger and clumsier and probably aren't a good match except with large hens, and they cannot cover as many as a RIR could. If you're talking bantam Cochins, they are fine with bantams and probably light breed hens but might not work for larger breeds.
Cochins should have their feather trimmed very short around their vents. They have so much fluff that when they breed they can't "hook up" with all their fluff. Above the vent on females and below the vent on males. My Cochin egg fertility tripled after I started trimming them.