We just say "no Huns or Spain" when we play.
In addition to horse archers being too powerful, cheap, and not requiring horse resource, Huns often have more production then their opponent due to extra production from stables.
If you are next to Huns and you are able to hold them back, then you lose the game (if good players are in the game) as you are dozens of turns behind in development.
Here is another observation - in a public game, Huns and Spain have the highest quit rate by far. Many Spain players quit if they don't find a wonder and many Huns players quit when their rush fails.
For the NQ group - one of my friends won on Pangea in less than 60 turns, and he was playing people with 1000s of hours of play.
It would be great when going random civs, some civs could be excluded.