MSN Explorer isn't bad but it does hog up a lot of RAM as Quantum says.
IE explorer loads faster for me in most cases
Netscape blocks pop up ads which I revere deeply LOL. It integrated Java (that is if you include it on the install) and has a better look to it. But sometimes it doesn't load all images right for some reason.
I really don't have a favorite, I just use whatever I am in the mood to use