Some factors to consider in your breed choice...
...are you looking for primarily eggs, primarily meat, or a bit of both?
...are you expecting them to forage primarily, or do you plan on the forage to be a supplement to regular
feed?
For my own chickens, I provide homemade feed to them (in pans) with free foraging 2 to 3 hours every afternoon (I use very little store bought feed, and eventually will phase it out altogether.) Based upon this feeding method, for egg production I like the red sex links that McMurray offers. They are rather mellow hens and lay large eggs. I also like the Americana and Araucana. The White Leghorn is probably the best white egg layer, but I'm not fond of their personality, so I no longer keep them.
I haven't raised strictly meat birds, but the Cornish cross is what people around here use.
Dual purpose breeds do an ok job at eggs & meat, but are not outstanding in either field. At least that has been my experience. I've had many different breeds just for the fun of it or just because I liked their looks. Some were better than others at foraging, but since I provide the majority of their feed for them, I didn't notice a big difference. Of the dual purpose breeds, I prefer the Rhode Island Reds.
Since some breeds can forage better than others, it depends upon how you expect them to do with your chicken
tractor set up.