We have Dark Cornish, Buff Orpington, RIR's, and Cuckoo Marans as our "main" meat birds. The Marans aren't a heritage bird in this country but they are great table birds.
I would have to say the DC's are the best foragers and most independent - they are on the flighty side though. A heavy solid chicken, they weigh more than they look like they should.
The Buff's are laid back, large, forage good - good sitters and mothers
RIR's also large, not as calm as buffs, same as buffs for forage, sitters, mothers.
There are alot of other breeds out there as well, I'm sure others will chime in.
Steve in NC