the chances of getting a virus with firefox is much reduced.
It also allows you to customise your browser to your needs and requirements through add-ons (download from the mozilla homepage) - for example i use the add-on to stop adverts being displayed on the web pages i visit e.g. no google ads, moving pics, or other rubbish slowing down the speed at which the page loads, i also have a very handy download manager, and an add-on that speeds up the load rate.
what else - it organises my bookmarks in a way i prefer (tabs along the top)
It hardly ever crashes
think that'll do - needless to say i much prefer firefox