I have Opera 5 for Linux installed on my FreeBSD box (it runs under Linux emulation mode), Netscape 4. 78 and Netscape 6 for Linux (same thing), and Konqueror (has an interesting feature. You can tell it to lie to the site you visit, by calling itself Netscape of various versions or IE of various versions, or Mozilla, or itself) from the KDE project.
I use IE 5 at home on my win95 box. It is the most stable, most extensible, and most user-friendly of the browsers I have.
NS6 is horrible resource hog, slow starting, and slow running. I haven't tried it on a Microsoft platform, but on unix it's unstable as all get out. Sometimes doing nothing more than clicking on a link when a page isn't fully loaded will crash it. I would still be using IE 4. 01 (and patches) for it's speed and stability, if it didn't have a faulty implementation of javascript, which gave you errors when none existed.