Chrome
Because I can do
and not worry about when a website's Javascript locks up the page and crashes everything.
Or a flash plugin, or just have the browser leak memory until it crashes (looks at Firefox).
Yes, it's a lot of web pages I have open. I often Multitask and will also open up new links in new tabs, especially on forums. It allows me to keep the core page, and just flick through pages and then close the tabs once I've finished with them.
I can also read something, minimise it and come back to it.
About the only thing I dislike about Chrome is that you can't get a permanent status bar down the bottom. Also the occasional Youtube video pausing halfway through!