A few months back I realized that my web browser of choice had become Firefox. This was despite my desire to avoid hype and stick to Mozilla's original "Seamonkey" browser suite (not to be confused with the new Mozilla Seamonkey browser suite!). Trying to identify how this happened, I think it was when Firefox improved to the point that it could handle most websites. Also, I finally had found enough add-ons to customize Firefox the way I wanted it. Even when add-ons were not updated to keep compatibility with newer versions of Firefox (like PrefBar), there are so many out there that finding a replacement is easy. The built-in password manager works with most sites and is free.
The only web browser which may have a chance of dethroning Firefox as my browser of choice is Opera. Completely free since version 8.5 or so, Opera features everything Firefox has and more. Since version 9 Opera has a built-in BitTorrent client - useful for downloading "Virtual Appliances" for VMware, which are often only available in BitTorrent format. Also, you can sign up for the free Opera Community which allows you to create a website and a blog, among other things. There is also a version of Opera for cellphones and other mobile devices. My Sharp Zaurus Linux-based handheld came with Opera pre-loaded. Opera for Pocket PCs really rocks. Although not free, it is the fastest browser for Pocket PCs, and easily displays websites which choke Pocket Internet Explorer.