From what I hear....the Buff Orpington goes broody alot. I just this spring got my little ones. They are 2 weeks old. Supposed to be great layers...heavy breed, and good in the cold. Im just not sure how they will do in this Indiana heat!
My little silver-spangled hamburg has decided she wants to sit on all the eggs! But my barred Rocks, Buff Orps. and silver-laced wyandotte have all sat on the eggs so I'm not sure if it's breed or just depends on the chicken!
Silkies and cochins were both bred to be good setters and moms.
My silkie will start to sit on any two eggs that accumulate, and has even gone broody with no eggs to sit on at all.
ETA: And to add to what hinkjc said, I have a few EEs, and the most Ameraucana-type one goes broody a lot, and is really tough to break out of it when she goes.
With the silkie, removing her from the nest persistently through the day will break her of it most of the time. When that one EE goes broody, it takes a cup of ice cubes under her a couple times a day to do it.
Bantam cochins, silkies, japanese, and belgian d'uccles are all great sitting hens. I have had my best luck with japanese hens and japanese/cochin crosses.
Here are a few pictures of my broodies...
BTW japanese left, bantam cochin/japanese mix right
belgian bearded d'uccle (mille fleur)
mille fleur left, cochin/japanese right
My hens seem to prefer nesting together as you can see from above.