I'm partial to Nubians, for the high butter fat milk. As that's all I have experience with, that would be my recommendation as well.

And because it's what my family kept when I was growing up. So when we found our little farm, Nubians was what I looked for.
We went to buy two milk goats. Two does in milk, that's all we wanted. Knew we wanted two so they would be company for each other.
Came home with nine goats.
The two does in milk we liked best had five bucklings between them.
The almost-yearling dry doe we loved on sight had a grade cousin doe that came with her for free because they'd never been separated.
We were down to six goats as of last week - lost the free grade doe to our own ignorance (horned goats + hay nets = bad bad idea

I'd never had horned goats before, only disbudded ones so, hard lesson to learn) and put two of the now-wethered bucklings in the freezer.
But after failing to find a registered Nubian buck with an owner willing to breed to outside does, I bought a buck I've admired from afar for awhile. So we're back up to seven goats. Lucky number, right?
-Sonja