If you're driving an 'old banger' which still provides reliable service, the maxim of "ff it ain't broke, don't fix (or replace) it" is probably a valid one. But if someone offers you a brand new, top-of-the-range, car free of charge you might care to consider the old saying about 'not looking a gift horse in the mouth'.
Nearly all of the 'regulars', here in AB's Technology section, use Firefox. Among those that don't, Chrome probably has more fans than Internet Explorer does. (The same is also likely to be true of Safari and Opera).
Firefox has long been regarded as a more secure browser than IE. Microsoft appeared to be getting to grips with security issues but the advice from the government agencies of two countries (France and Germany), not to use Internet Explorer, knocked back Microsoft's reputation again.
Firefox is a great browser when used 'straight out of the box' but it really excels when used with its optional extensions. The most popular ones, among contributors to this site, seem to be the British English dictionary (because posts like this one are automatically spell-checked by Firefox) and AdBlock Plus (which gets rid of all the annoying ads, so that the page loads far faster). Google have just introduced a range of extensions for Chrome, but there are still far more available for Firefox. (Microsoft are still years behind, with no sign of any useful extensions for IE at the present time).
To return to my earlier analogy, why not keep your 'old banger' in the garage but park the Lamborghini alongside it? Installing a new browser doesn't require you to get rid of the old one, so you can have several on your computer and then decide what's best for you.
Chris