If you want chickens that lay well, hatch eggs from chickens that lay well. If you want good meat birds, eat the ones you don’t want to eat and breed the ones you do want to eat.
Breed is really irrelevant. Back before the mid 1900’s certain strains of some breeds were bred as meat birds, but since then the Cornish Cross have totally taken over that market. The meat strains of those breeds were totally lost. Now they are basically dual purpose chickens, no real difference from any of the other dual purpose chickens.
There are a few people, very few, that are breeding certain breeds, mainly Delaware or New Hampshire, to try to get back to the traits that made them decent meat birds; good conversion of feed to meat, fairly rapid growth, and decent size with a certain mix of white to dark meat. If you can find someone who is doing that with any chickens, heritage meat or just a barnyard mix, you will be much better off than any hatchery birds regardless of breed. I’m not talking about someone breeding just for show, I’m talking about people that know what they are doing breeding for the meat qualities.
Many of us take the route of getting hatchery birds and selectively breeding for the traits we want. As long as you know what traits you want, keep it fairly simple, and are pretty ruthless in selecting your breeders you can make some good progress in just a few generations. The more traits you select for, the more complicated and slower it is to get where you want to go.
The meat birds are generally light colored, either white or buff. That’s because when you pluck you always leave pin feathers. With the darker birds those really show up. With the lighter colored birds they are still there but the carcass is much prettier.
You cannot beat the Cornish Cross for producing meat, they are specialists. But unless you go to a whole lot of work to restrict their feed, they are not sustainable in the long term. You really need to always buy chicks.
Good luck with it.