Firefox is much better, but I personally prefer the Opera browser. first, it is lightweight, very fast, with excellent ways to manage cookies (if you are like me, you could set it to delete cookies when you exit from the browser). One interesting feature is the convert to speech ability, wherein it will read out on your speaker the selected text being displayed, This has a downside, as the mixed Hindi and Englis words sound funny.
If you looking for speed and security, I feel Opera is way ahead. The only problem with it is that it does not behave correctly if there is an Activex control on the page.