How is it "technicaly" better? Opera is a good browser, but support and developements from both users and developers is minute compared to that of Firefox.
It just works better, it has easier to use interface (the newest Opera), safely remembers passwords and steals less resources.
I don't know about Firefox but opera is also 100% pendrive compatible which means that you can take your personalized browser everywhere with you and it's safe.


Sometimes it crashes. That sucks.