I quite liked "Fire" but found it was lacking in a few features I needed, so I eventually moved on to "X-Chat" (the Aqua version, not the X11 version) which I am very happy with.
Fire can handle the basic functions but not e.g. /nick /ping /cping commands. I have not tried ping with risen status with Fire.
I use Ircle. You can get that from versiontracker.
That has full commands.
There is also an irc program for this this site - it connects to out irc only. - do a search for the Irc client on the site and you will find the url to get that client as well.
I tried Ircle too, but decided I did not want to pay for it (and therefore would not use it, to be fair), especially as X-Chat seemed to work just as well. The only extra hassle I had with X-Chat was that I had to set the port range for DCC file transfers, while a default range is already set in Ircle, but this is easy enough to do.
I also found some other procedures (specifically to do with authentication by a "bot") worked under X-Chat but not under Ircle for some reason.
I'm not shooting down anyone else's views, just offering my own experiences as I had to play with a few different programs before I finally settled on one!