My guess is that most people use Irssi or Weechat. Would be surprised to hear if anyone uses ircii or mirc, and the only way to find out is to ask.
What's your favorite client?
I'm using irssi as well (would a thread about irssi plugins be worth?). Before that, epic5
I'm using irssi as well (would a thread about irssi plugins be worth?). Before that, epic5