I haven't met an Undernet
IRCop yet, but I really prefer Undernet over
EFnet. Mainly because there are fewer people, so you get to know the regulars quickly. Of course, having a smaller population is also a bad thing if you're into some
obscure topic or looking for a
local scene. But places like
#Computers,
#Programming, and
#C have enough people to entertain you.
Don't get me wrong though, Undernet isn't perfect, places like
#C++ are places to stay away from. Overall though it's a good community.