Picking Firefox’s best feature is like asking what is your favorite part of a vanilla ice cream scoop. It is all good in my opinion. One person at least thinks that Firefox’s “Quick Search” feature beats them all.
Before I began using Firefox, I used a IE mod called Avant Browser. Avant was fantastic at the time, it added Tabbed browsing, themes, domain aliases and a little thing called quick searching. If if you are all familiar with Firefox, you are probably familiar with Quick Searching. In my opinion, it eliminates the Search box, which is by default, turned on, in Firefox.