I use FireFox cuz, I dunno, at some point I heard it was good, so I tried it, and I don’t have any problem with it. My daughter swears by Google Chrome and scoffs on my browser choice, but it’s important to never listen to kids.
I’m never going to stop using firefox unless it’s discontinued. I need my adblock and remove-it-permanently addons. I also like that firefox is minimalistic if you want it to be. I have two bars of stuff, one that is similar to yours and then a second line with all my most frequent bookmarks.
I used my friend’s computer last weekend and she uses IE. There was so much crapware installed that the menu bar took up a full third of the height of the browser! Christ, lady!
Addons
I use Firefox.
Firefox has been my primary for a long time. In spite of the fact that it takes about 5 minutes to start, I still use it because (a) it’s what I’m used to, and (b) the Reload All Tabs thing. Back in The Day, I used Netscape and remained a loyalist when IE came to be, but eventually it was consumed by AOL and became a bloated piece of crap. I hope Firefox doesn’t suffer a similar fate.
I do use Chrome pretty often nowadays, though. After buying an Android phone last year and discovering that it required a Gmail account to activate, I decided to use Chrome for Gmail and other Google-centric stuff. I also use it to access one of my Yahoo accounts, while Firefox logs into the other one, so it’s kind of an alternate e-mail client.
Huh, the only wasted space in my chrome is the omnibar. The section below that is filled with my most used favorites. I think if that’s your biggest problem with chrome the fault lies with the user and not the browser.
I use chrome because it consistently loads faster than other browsers and its extensions library is close to firefox in terms of modifying the browser.
Firefox, because I’ve got adjusted just right and don’t want to take the time to do it all over again in Chrome. Also, I hate that Chrome’s tabs are on top, although that’s not so bad now that they fill up the title bar.
I use Internet Explorer. I switched to Firefox a few years ago but after losing all my bookmarks on two separate occasions while acquiescing to an update, I blew Firefox off and went back to IE where I’ve never had a problem.
I use Firefox because of Adblock Plus. For whatever reason this simple program hasn’t made it to the IE or Chrome worlds yet. In FF it’s so simple. Go to add-ons. If it isn’t in the recommended add-ons (it usually is) take two seconds to find it. Install in seconds. No more frigging ads.
Chrome was interesting but would not let me minimize a page until it was fully loaded, which made browsing porn into Russian roulette. This was an early version so they may have fixed it by now but nothing could put me off a browser faster.
Opera - for mouse gestures
Whenever I use a browser without mouse gestures it feels like I’m working with one hand tied behind my back
Tried Firefox with a mouse gesture plugin but it didn’t “feel” as good - I’m probably just used to the way Opera handles things
I use Firefox because of the addons. They seem to have mostly solved their speed and stability issues. I was on Chrome for a while last year while Firefox worked it out.
Now with my nifty new TabGroups Manager that lets me have different “folders” of tabs, it would be hard to switch to anything else.
Chrome just seems the fastest, least cluttered. I used to use Firefox. Some sites I will open with Firefox. I like the homepage for Chrome with the recently/often visited pages showing up as icons.
eFirefox. Add-ons, habits, security, so-on.
I’m not convinced Chromium is faster. Maybe it’s because I’m on a linux system, but I just timed them starting. 10 seconds for FF to start and completely load 6 tabs, 8 seconds for Chromium but with only one tab open.
In fact if I was going to change it would probably be for Midori, rekonq or lynx. Pretty, fast and secure, in that order.
Firefox, for Ad-Block and for Web Developer Toolbar. And IE Tab 
I actually find IE to be faster at some stuff now, but I rely so heavily on the Web Developer toolbar and Ad-Block that I can’t switch.
Chrome seems “silly” to me. I can’t move around in it.
I’d actually like to use IE 9 but until they support add-ons, sorry. Firefox it is.
ETA: Forgot Greasemonkey, and Facebook Purity. Holla!
I use FF for the addons, but wow is it a RAM hog - I regularly find it using 500-750MB of RAM when I have more than 5 tabs open.
So I’ve toyed with Chrome, but I really like my addons - pixlr integration, paned tabs, multi-row bookmark bar, etc. And I would be lost without FastestFox.
I’ve been thinking about it for a few minutes and I can’t come up with a situation where I would need to reload all tabs. Yet that seems to be really important to several people here. A little help?
Let’s say you’ve got three SDMB threads open, CNN’s home page, and a liveblog of an Apple event. If you are “grazing” for content, you can reload all tabs, and skim each tab for updates, instead of having to manually refresh each one.
ETA: Here’s a good work-related example if one works with a web-based reporting tool, like a Salesforce.com. You can have several different reports open in separate tabs, and refresh them all at once to get current data, instead of individually.
I’ve been using FF for a few years and just haven’t had a reason to change. ABP is HUGE to me. I never knew Facebook had ads until I was looking over someone’s shoulder at their page on a different computer, and I was like, “what’s all that crap? I never knew. Why don’t you have an ad-blocker?” I have no understanding or comprehension why people would voluntarily put up with ads. Even when I was just a guest on the SDMB, I never saw the ads!
I’ve been taking all the upgrades of FF as they have come, and yesterday updated to the 4.0 beta. I think it’s set up more like Chrome in the 4.0 but can’t say for sure since I’ve never really used Chrome. The tabs are all the way at the top now, anyway. I like it so far. Some of the buffer lag I was getting on the 1080 YouTube videos seems to be gone, so that’s good. I don’t use many add-ons or extensions, though, so I’m probably less likely to run into beta bugs than a lot of people.
Firefox. I can’t life without NoScript.
I used Firefox for years, exclusively. I switched to Chrome recently (within the last week actually) because, I kid you not, it ran a Facebook game I play with my girlfriend a whole lot better. Not just, “I don’t know it sure seems faster,” but “Dear God, wtf is wrong with Firefox?!” faster. Sold.
Downloaded Ad Block Plus on it, and that’s pretty much all I need. And for the first time I can ever remember, it synced my bookmarks from another browser flawlessly and without a problem. And syncs my bookmarks across computers flawlessly too. Sold x2.
Firefox for me. I used to be an Opera fan and was loyal for a long time but FF had something I wanted (can’t recall) and I’ve used it for the past 6 years. Love the add-ons although I only use a few. Ad-block of course.
We are all different. I have 18 tabs open in FF at the moment which is average. Sometimes there will be 25 and I have to discipline myself to close tabs. My rule is only 10 open tabs but… 
Generally some are there just to remind myself to do something.
For example, I wanted to make a donation to the Salvation Army for their efforts on the Christchurch earthquake. I opened a tab to do it, couldn’t find my credit card, so shut down my laptop for the night. Next day all tabs reopened and I remembered to make the donation.