Chrome > Opera > Safari > Firefox > Sending messages across the ocean in a bottle > Internet Explorer.
In chrome, each individual tab is a separate process. If one freezes up, you can individually kill it. With IE and FF (not sure about Opera and Safari), one tab freezing up will freeze the whole browser.
Chrome and Safari have beautifully smooth systems for moving tabs to one window or the other. Opera has a good system, but the interface itself is clunky. IE and FF fail at this as well. And yes, this is a feature that I use excessively, so it’s important.
The simplicity of design for Chrome and Safari gets them tons of points as well.