Browser ennui

I’ve had a problem deciding what web browser I should be using.  I’ve been using Firefox for a long time, but for some reason the current versions on Ubuntu like to freeze a lot, causing me to have to force quit and then start it up again.  Its also kinda slow, both in opening the program itself and in opening new webpages.  I’ve also been using Chromium, which is what Google Chrome is based on; however, its pretty new and not solidly mature yet.  Also, the development version of it has been suffering from some bugs recently.  So now I’m writing this from Opera, which is the third of web browsers that I have been considering.  It seems fine so far, but it isn’t open source, which is kind of not good.  Also, I don’t really like the way it does extensions… I would rather them just be in the browser bar rather than separate applications that hang out on their own.
Any suggestions for which browser I should go with, or new browsers to try?  In the end, it doesn’t really matter; all of them deliver the same thing: the internet.