You'd probably get different answers. Mine are/were mostly Nubians and NubianX.
They give enough milk with high enough butterfat for me, and if someone wanted to process extra males they are big enough.
Some people like Nigis. Hardier than Nubians and more likely to breed year-round. More kids produced and higher butterfat as well as good milkers for their size.
I'd thought about Kinders, produced by bloodlines that combine the two. If well bred, supposed to give the best of both along with large numbers of kids.
I was initially interested in Saanens too, but they aren't very common around here.
That answer is going to vary according to the needs of the owner. I settled on mini-manchas because they tend to be quiet, give plenty of milk and that's what I have space for. If I had alot of acerage I would probably have a few different breeds.
I have a Nubian, Brown Sugar, and a Nigerian Dwarf cross, Gidget. So far, they're both dry. (Don't really have the room needed to breed them.) But if I did, I'd keep one of Sugar's babies, and try to have a kid in the spring and the fall.
I'm a bigger fan of hybrids....because hardiness is important to me. Fewer crises=more production, whether it be for dairy or meat. Since dairy is more important to me right now, I am using dairy bucks, four of my six does have heavy meat goats in their backgrounds....two pygmy-x's and two with Boer in them.
The two with Boer in them are interesting. It will be interesting to see what they can produce as far as milk is concerned. Ginger is 1/4 Boer, 1/4 Alpine, adn 1/2 Nubian, so 3/4 dairy, but she is hefty and has the thickest coat that allows her to be out in the rain and snow. Her daughter is the product of a purebred La Mancha buck, so she is 7/8 dairy and 1/8 Boer and looks like she will be just as big and sturdy as her momma. If they can "put it in the bucket," they will be the perfect homestead goats.
I will see what my pygmies give me with the Alpine buck they are bred to. They have been completely free of any health issues in spite of neglect in their early year or two, before I got them. Or maybe because of it.