As-salaamu `alaykum.
I've been a long fan/user of firefox... really long. I really loved tweaking it, tailoring it just how I wanted it. I love the keyword search facility!!! One thing that upset me is that Google have discontinued their Firefox Browser Sync... Apparently they have made the source code for it open, but now I can't get any of my bookmarks! Let's hope it comes out on chrome in future...
I think Chrome is great, it annoys me that when you're downloading seeing it doesn't warn you prior to terminating, that you have downloads running!!! It also uses too much memory when running flv files on youtube etc... but I assume they will be fixed before release.
Konqueror is more than just a file manager, if you use KDE it may be your default browser. One feature that I love about it, is how you can split the windows! In other words, you can view two pages at once, in the same window! This is really useful for web programming; I split the window horizontally first, with the webpage at the top half, the bottom half I split vertically, one containing the server files (as we know it is a file manager too, this wouldn't be possible otherwsie), and the second displaying my own files...