I have raised all the breeds you are mentioning here, and BY FAR, a good Cornish will save you money on feed. The problem with Jersey Giants is that they take forever to grow out. They basically put on frame the first year and meat the second, so for a meat bird, I found they really aren't part of the answer. Orpingtons don't take that long, but they do take longer than a Cornish by a few months to get the same amount of meat. I have had hatchery Cornish that dressed around 3-pounds at 4 months. But the good quality Cornish I have now dress better than that at the same age, like 3-.5 to 4-pounds. I am talking all cockerels though because the hatchery pullets were sold and so far I have not butchered any of my pullets from my current flock because I am waiting until they get a little older before culling. As for eggs laying, your hatchery birds will probably lay better than that, mine do. The better quality Cornish bred closer to Standard are not great layers, but if you are looking for bird for meat, then there is a compromise. There is another thread that is supposed to be more about crossing Cornish for meat: https://www.backyardchickens.com/t/316007/red-laced-cornish-x-and-project-talk-pics-p-8 If you are thinking at all about crossing to produce meat birds, including Cornish is a must. I have been crossing Buckeyes and Dark Cornish this year (hatchery type) and producing beautiful birds for both eggs and meat. Even the pullets are little meat monsters. So, I hope that helps in your search for answers.