According to previous research that I've done, (and some recent to brush up haha) :

• On a scale of Milk vs. Feed, Nigerian Dwarf goats will produce more, for less. They average about a half gallon a day, versus the Nubians output of around a 3/4's of a gallon, to a gallon and a half a day if you have a really good doe.
• A con for many small breed goats (ie: Pygmy, Nigerian dwarf, etc.) Is that thye are more prone to certain diseases than larger ones. I don't remember if this is because of the breeding that took place to make them "mini" or what, but it could be something to look into.
• If you end up getting stuck between the two breeds, have no fear! You could look into Mini Nubians, which just happen to be a mix between Nubians and Nigerian Dwarf.
• Milk fat content: For more ease making cheeses and butter, you would need a higher milk fat content. Nubians average around 4-5%. Nigerian Dwarfs are infamous for the higher milk fat content in comparison to other goats. It ranges from 6-10%.
• Milk flavor: Nubians are known to have sweet tasting, smooth milk. Nigerian Dwarf milk is said to be creamy and sweeet. Apparently it is one of the best tasting goat milks out there due to the higher fat content.

Hope all goes well for your goat rearing adventures!