The best replacement for mirc is xchat.

The best alternatives to mirc are rated as following:
★★★★★  xchat
★★★★  irc
★★★  chatzilla
★★  hydrairc
★★  hexchat
★  icq
★  pirch
★  pjirc
  mibbit
  icechat

Your alternative for mirc is not listed? Suggest!
Speaking about mirc, one probably shouldn't forget about invision.

Other search terms related to mirc and their ratings are:
★★★★★ invision
★★★★ download
★ tor
★ downloading
proxy
ssl
You have in mind a companion for mirc and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mirc in all years. Click on graph for more.
mirc
xchat
irc