Oh no...this is gonna turn into 1 big flamewar, I can already see it
I mostly use Netscape(communicator 4.74) simply coz I'm more used to it. However, most pages are coded with IE in mind, so may look weird when viewed with Netscape, so sometimes I use IE5 too. IE is more fault tolerant when it comes to HTML, so if you make a mistake, IE will still try to guess what you're doing, but Netscape either doesn't, or guesses pretty badly.
When creating websites, I prefer IE coz things work easier/more convenient. But when viewing websites, either is fine for me, except Netscape seems to crash more often.
One small thing that bugs me about IE5 is that when I press Alt-F to search the page, the menu pops out sooo slooowly...at least compared to Netscape, which is instantaneous. Also, I can't press F3 to search, or even search again, like I can in Netscape. Pressing F3 will prompt a File Search instead.