I really have not seen anything that jumps out and says that you should be using one over the other. Firefox does have an expandable sidebar for bookmarks or history that I kind of like. There are also alot of extensions that you can get for firefox but overall I guess I like them both. I would just try using Firefox for long enough to get use to its features if I were you. If you do that then you can form your own opinion based on your individual taste.
Since the question arising on Firefox is open, I was wondering what differences anyone has seen between it, and Safari. I have been using Safari with but a few problems for some time. Is there an opinion as to which is better, it at all? I am using it with OS 10.3.6 on two G4's, a Titanium laptop, and a 1.25 dual processor, both with plenty of RAM. There is, however, one specific question. Some sites I can access fully with the laptop, but not with the desktop, even though they are virtually the same hardware & software.