Well, i can't speak for OSX, since i'm using MacOS9.1, but i have got Netscape Communicator 4.76, Mozilla 0.9.6, Internet Exploder 5, Opera 5 and iCab 2.71 installed on this Mac.
All have their pluses and minuses, but Opera is by far the best!
I expected a lot more from Mozilla, but nope, it's just boring old same old same old. Actually it's noticably better than Netscape (and by extension IExplore) but Opera still whips the pants off it, sorry!
iCab is good in a lot of ways, but it crashes nore than is good for it i think, and i will eventually have to pay for it which is not ideal. I get something like 5 months of trial with iCab though! which is pretty good for a pay program!
No, Opera is best! sorry! it's also totally cross platform, what with versions for Linux/UNIX, Beos, SunOS et cetera, et cetera.
rant over...