I choose Opera for this survey a while ago, here's why. Mouse gestures is my favourite feature. I vaguely remember that Chrome has a plugin that can also enable mouse gestures. The speed dial is another great feature I like (and when combined with the mouse gesture for opening a new page, I can get to my favourite pages very quickly).
For people with slower internet connections, they have a feature called "Opera Turbo" which tweaks settings for slower internet connections. I also use Opera as my email client.
I wish Opera would have more plugins and this is its weakness when compared with Firefox (which also happens to be Firefox's greatest strength).
To read more about Opera:
Opera: browser tips