New Hampshire Red is, in my opinion, the best dual purpose bird. With Delaware's coming in 2nd.
When I raised birds for the live bird markets, NHR was the best. I select bred for several years to get birds that would reach 5 lbs at 15 weeks. These are roos, of course. The hens would come in around 4.5 lbs. I didn't put any emphasis on egg production but would still get about 70-75% lay each day.
What you really want to look at is feed to weight gain. With dual purpose meat birds, you really want no more than a 4 to 4.5 lb of feed to equal 1 lb of weight gain on your birds. I was actually down to 3.75~4 / 1 on mine. But I live in south Texas and it stays warm here and they don't need any extra feed for warmth.
Also, here in TX, the bird markets didn't want Delawares as they did not want a white bird as it reminded them too much of Broilers. But Delawares do have a very similar weight gain to feed ratio as NHR's. Maybe even a bit better.
Hope this helps.
Danny D