Hello and thanks for the interesting post.
First I'd like to mention that I do some web development and I need both of these for testing purposes. However I certainly can't live without Firefox and its web development add-on: Firebug*. Firefox also has other vast amount of add-ons like Httpfox which is used for tracking request, response, cookie and header data typically obscured from a regular internet surfer. The analogue of these tools in Google Chrome is the Javascript console. The Mozilla development community is probably one of the biggest so I think FF has more add-ons than other famous browsers. And these add-ons are certainly not restricted to web development only, we have some for layout and tab display, FTP clients, extremely customizable ad blockers etc... However Google Chrome also has some quite useful and handy add-ons that I often use, like the Chrome SEO plugin which displays some search engines data like (number of indexed pages and back-links) for any site and for major search engines like Google, Yahoo, Bing... I also like the Resource Tracking tool of Google Chrome which is a tab from the Javascript Console. It shows how much time each element on the page (scripts, CSS, graphics, HTML) takes to load and is quite useful for speed optimizations. That last tool probably has a nice analog in FF but haven't found it yet

. Anybody... ? I also find that Firefox has one of the most accurate rendering algorithms regarding page elements styled with CSS. From my observations although Chrome sometimes crashes or displays CSS improperly, the pages are rendered faster than in FF for which I find Chrome superior to FF regarding rendering performance and Javascript. Probably in future these bugs will be fixed and Chrome will be even more preferred than today... I also find some memory management/recycling issues in Firefox that make it crash or drain a great amount of memory from the system which typically occurs when many tabs are open with a lot of flash content in them and in MS Windows.
Having said all that, I ultimately prefer Firefox as my default internet browser.
*Web developers not familiar with Firebug should definitely give it a try!