Most likely to go broody hens?

[PlagueDoctorFarms]

Agreed. OEGBS are a much better choice for OP's setup, silkies are in no way shape or form a good bird to free range

I haven't found silkies to be good for anything just joking

 

[PlagueDoctorFarms]

Law Grey Gamefowl hen with spurs, she is a VERY successful brooder

 

[HenriettaPizzaNolan]

I only have one but my Black Australorp from Meyer is a relentless broody, and has proven to be a good mother recently by raising 7 chicks I gave her. When she's not broody, she's also an excellent layer, forages well, and is fairly predator-aware. From what I know, this is all typical of the breed. I've heard Orpingtons are similar in these respects, but my young Orp is yet to go broody.