Opera or Firefox

I was always wondering that, why I like Opera more than firefox. Although, Mozilla Firefox is technically much better, as it has a lot of plugins and everything. Even in google feedback, I find "Google Chrome", "firefox" and "MS IE" but not Opera. Firefox is a name in Internet browsers. Its a trademark and that is not the case with Opera.
I knew, its about the interface. Well, today I managed to compare them side by side. What I found was very interesting. The Icon of Opera is very simple and it has a very dark color, color of passion, "Red". Opera had another thing! Every option on Opera was much large and visible than in firefox. Perhaps, these were the things that appealed to my psychology. It may not be a universal case. It was with me, it was a mystery for me and I solved it. Bravo!! lol! :)