The single feature that forever ties me to Chrome is tabs on top.
On top of the address bar isn't the point. It's a nice touch that emphasizes the metaphor for "real" tabs, like on a paper folder, but it doesn't have the huge usability bonus of Chrome's implementation.
The important thing is that in Chrome, the tabs are on the very top pixel of the screen (in Windows or a Linux UI with no top bar). Since I browse with a hand on the mouse, this means that I can switch between tabs by chucking the pointer at the top of the screen and scrubbing left and right, instead of having to pay attention to vertical alignment.