Thunderbird is a pretty good email client as well. I start using it every now and then but in the end, I'm forced to admit that I don't really need anything more from email that I can't do just as easily in the browser window.
I used Firefox for years before switching to Chrome, which I found to have better performance. I don't know if that is still the case but you really get attached to a browser, it's almost like a 2nd OS inside your main OS because online browsing is such a major part of computer usage these days. And it takes a while to get settled into a new browser. All those settings, the UI layout, bookmarks, extensions and add-ons. Switching browsers is a little like moving house.
Opera I never really got along with and then one of the guys behind it annoyed me a few years ago by mouthing off about how "unfair" it was that Microsoft bundled IE with its OS and how the EU was right to fine them hundreds of millions of $$$'s. At the time I thought the EU's extortion of Microsoft profits was nothing less than an act of criminal theft, and I wasn't about to install the browser of a man who stood behind this extortion. I've probably calmed down a little since then and would be open to trying this new Opera browser, once it's added a few features (I've also read that it's not that stable yet).