I'm normally a Firefox user, although sometimes I will load up Safari because it's faster. However, I've been using Camino for the past few days and I'm really liking it. It has the loading speed of Safari but the rendering engine of Firefox/Mozilla. There are some thing about Firefox I miss, though--
1. Tabs that can be scrolled and rearranged.
2. "View Selection Source"
3. "View Background Image"
4. Searches that open in a new tab instead of the same tab
5. Recently closed tabs (for accidentally closed tabs), or at least the ability to turn off the tab closing "X" on each tab. They are far too easy to click.
6. Firebug/YSlow - These are not as critical. I found myself leaving them turned off in Firefox most of the time, anyway, since Firefox has been running slowly for me lately as well as occasionally bugging out to the point of needing to be restarted. Camino does have the Mouseover Dom Inspector and some support for GreaseMonkey scripts, but those are not quite the same. If I really need Firebug functionality in Camino, I can always use Firebug Lite.
7. The View Source, Previous Tab, and Next Tab keyboard shortcuts are different from both Firefox and Safari. Fortunately, they are easily customizable through OS X's System Preferences.
I DO like that FlashBlock functionality is built into Camino and turned on by default (requiring flash movies to be clicked before they start to play). That's quite possibly my favorite add-on for Firefox.
I'll probably keep using Camino for now and fire up Firefox only when I really need those web development tools. The zippiness of Camino makes it feel like Firefox first did when I switched from Mozilla. Perhaps I could try re-installing Firefox and see if that helps, but at the moment I'm happy enough with Camino that trying to fix my Firefox installation seems like more trouble than it's worth.