Why do you think Internet Explorer is superior to FireFox?
So, you want to know what I value in a web browser? First, I could ask why would it not be superior? There are only few UI issues that make firefox better, and those can be worked around with plugins. Perhaps, as a programmer, I see IE differently than you do.
One big bonus is being native to the system, which means I can do things that are impossible with Firefox. For example, can you have Firefox in a toolbar? Well, you can have mshtml rendered page there. Go ahead, right click taskbar and go toolbars->new, and type "
http://microsuck.com/forums" as the directory. While this specific feature isn't critically important, it's just one of the many things that result from the design. In windows world, objects are more useful than applications.
Also, I like the rendering engine better. While it's true that mozilla renders CSS better, having done some little webdesign it blows mind how ambiguous some of the explanations are. CSS isn't very well specified, and trying to implement it will lead to implementation differences between different browsers. Obviously, such differences will be blamed on microsoft for no real reason, just because MS interprets things differently from others.
For things that matter, IE6 functions great, and I see no reason to use an alternative browser except for situations where braindead webdesigners have designed that the site will require flash and javascript to function at all, and for some reason I'm forced to use the site.