we had have one nubian buck, never ever again, then at shows (i helped a few people show theirs) when one was taken away, all the nubians there freaked out, not joking! my shirt had a hoof print from one jumping on my back will i was trying to keep it calm will her buddies was in the show ring (ouch) from my experiences i dont think for some one starting out with goats it would be a good idea to get some, and also, even if they are minis, nubians can be HUGE i saw some the size of our mini horses, that were not minis, but still 0-0
on the mini part if you want them smaller then yes breed them to a niggy (nigrian) but if you like them at the size they are, breed them to other minis of their breed and work on body type
we ourself own 4 niggy grades (meaning no papers) that if they can will test our way to keep them in (most goats will, but because they are smaller they have a better chance of getting out DX) and we also have alpine, that for her breed is small and super sweet, but from what we understand most alpines are, stubborn. and we also have a lamacha that is small for her breed, but her temperament is just right (they are suppose to be the most docile goat breed out there)
if you can go to some goat shows and ask the breeders about their breeds and why they like them

just make sure they the goats are CL,CLA free, there is some other stuff you need to make sure they dont have, but i cant remember