
Talking about Firefox, there is not much visible difference between FF3 and its previous version. But Mozilla has improved the browser code, which reflects in the increased speed and better memory handling. The other most notable features of FF3 are resumeable downloading across sessions, one-click bookmarking, full page zoom, enhanced add-ons manager, bookmark tagging etc. The best thing about Firefox is its wide range of plug-in and high degree of customizability.
Opera also has been doing a good job and is really a good piece of work. Although Opera is not open source as FF but still it has made remarkable innovations, remember tabbed browsing, mouse gestures and speed dial. Opera also is the browser that provides the most functionality upon initial installation. It acts as a complete browsing suite which includes a RSS reader and the only browser that has a built-in mail and chat client.
I first tried Opera from the days it was a adware and the main reason was tabbed browsing and faster page rendering. From those days Opera has came a long way. It has kept on improving and getting better and better. Features such as Quick Find, allows you to search for a website that you have visited over the last few days and ability to synchronize between your Opera cellphone browser and your PC Opera come quite handy. Other newly incorporated functions are same as in Firefox, so its on par with FF.
Now which browser you should use completely depends on personal choice and browsing style rather than to do with mind-blowing features. This debate is like Pepsi Vs Coke or Mac Vs Windows and the fans of either browsers wont be influenced by what other has to say.
I have installed both of them on my system and use them depending on my need. For specific purpose such as web development I use Firefox but for casual browsing I prefer Opera. Personally I feel, Opera seems to be faster than Firefox on slow connections which may be due to Opera's better caching. If you have a slow connection I would recommend using Opera. For now, Firefox3 would be the default browser on my computer because of its vast plug-in. But that doesn't means I will abandon Opera, it still would be there on my desktop sharing space with Firefox.
What do you think, which one is for you? Share your opinion. Get the latest version of Firefox here and Opera over here.