I may be a minority regarding this choice, but I’ve always preferred xchat-gnome to plain xchat as my IRC client. Its minimalist interface fits well with my GNOME desktop, and the preferences dialogue is much cleaner than in regular xchat.

The only annoyance is the user list, which upstream insists on hiding behind a button despite all pleas to provide an option to show it in its own panel. Finally, I wrote a patch adding that option about a year ago, and today I fixed a bug with UI freeze in it.

I’ll try to get it into Lucid, but in case the core devs decide not to sponsor it, I’ve made a PPA for Karmic with the patched version.