Nubian goats, for plenty of good milk. I'm vegetarian- so beef cattle aren't important to me but oxen for pulling a cart on the property and providing lots of fertilizer could be.
I have thought about raising Icelandic sheep when we get up to the farm. They are very hardy in this environment (Maine) and come in a variety of colors. But DH doesn't like lamb, and I'm not really interested in breeding them just to sell. Can't stand the taste of goat milk. So, it would probably be a small cow, if we get any big animals, and maybe a goat for company.
I have all 3. I am giving up the goats, however, as they keep tearing down fences and are much harder to deal with. The cow provides more year round, but we love lamb and the hair sheep are so low maintenance. Hair sheep are not seasonal breeders, so you can get 3 lamb crops in 2 years. Mine graze with the milk cow. I have noticed the hair sheep tend to forage more llike a goat than like the wool sheep I had before. but much easier to contain than goats. I also have LGD's to insure their safety. So it depends on what you want. A cow will give you meat as well as dairy, and cream for butter and stuff, which a goat really isn't going to do. I love the sociability and personalities of goats but not the headaches they bring with it.