Good morning!
The hatchery Delaware I had was good for NEITHER eggs or meat. WAY to slow maturing and growing. Once eggs were finally laid they were on the small side.
So, IF that is the breed you go with for a dual purpose intention, please make sure you buy from a good heritage line!
French black copper Marans... have been my favorite so far for growth rate, personality, marketability, flavor, hardiness, fantastically capable broody's (FAR superior to ANY Silkie), foraging ability, beautiful eggs... all around great birds IMHO... noting mine were NOT hatchery birds and that may effect ALL aspects.
No dual purpose bird is ready for processing (size wise) before 16 weeks in my experience. This is why I have a grow out pen because most are actively trying to mate before then. Also too slow for ME.. were Orpington, Brahma, and Faverolles. But I am of the mind that chickens is MY hobby and eating is a side bonus... therefore I raise what I enjoy keeping and no breed is above gracing my table with the extra cockerels... even Silkies!

I have not personally tried Buckeye or Dorking yet... both said to be good dual purpose breeds. So far most birds I raised were not the same in person as they are on paper, recognizing that we and the birds are all individuals... pointing to the need to decide on a breed and select HARD the stock you will keep.
Check out these comparison charts...
https://livestockconservancy.org/images/uploads/docs/pickachicken.pdf
http://www.sagehenfarmlodi.com/chooks/chooks.html
Good luck!