Opera is pretty bad, but I use it on the Wii, like I have any other choice....
But yeah, it actually runs pretty good. But I would NEVER use it on a computer.
IE is a joke. Its way too messy and outdated for me. Although it can easily be argued against, I say it doesn't deserve the usage it gets. If anything Google Chrome and FF deserve to be top because of their universal uses.
I use FF on my PC, but I really never use the PC, so I have to say my personal best is Safari, no doubt. I of course use it on my mac and my iPhone, but FF is a close second. But If you have a mac, Safari is the answer, because they are literally made for each other.