As Mike suggested, there is always Opera, which has remained under the radar and while down there driven a lot of the innovations behind the other three browsers.
I'm torqued that Mozilla stopped allowing the WM_CLASS variable to be changed... is messes with my ability to manage several iterations (through profiles) to be open at once.
... and they stopped developing Prism, which would have been a really nice stripped-down browser for me to use in one of those iterations...
I may end up going to some of the more esoteric Linux browsers. With the profiles I have, they might as well be three or four different browsers.