I decided to give Opera another try. How is Opera so much insanely faster than Firefox at rendering? I wish I knew the answer to that. Supposedly the 9.5 alpha is going to be faster still. It's currently hard-masked in the portage tree so I'm going to hold off trying it for a while, but that would be nice to see. Either way, even with Opera 9.23, page transitions especially are noticeably faster than Firefox, and page load times tend to be fast enough that you can appreciate the difference.
Themes in Opera are still 100x easier to find and download and install than Firefox's. And a lot of them look really good. Maybe someday Firefox will get this right. (3.0?) There are a lot of fairly minimalistic Opera skins, which is what I like. But also a lot of the typical Vista clones, and Tango and KDE/Gnome lookalikes etc. On the topic of the interface, Opera comes with way too many buttons and sidebars enabled by default, but you can strip all of that crap out of it and get something even more minimalistic than Firefox if you want.
The preferences menu of Opera reminds me a lot of KDE, in the sense that there's a config option for absolutely everything, if you're willing to dig through a thousand dialogs and collapsable trees of options to find them. I learned recently that there's an
opera:config similar to Firefox's about:config which lets you get at any option you'd care to edit, which is a blessing. Plugins (e.g. Flash) seem to work OK also. I think I recall that being a problem in the past, but I didn't have to do anything to get Flash to work in Opera this time around.
Opera is not tied to Gnome/GTK, which is another immensely huge advantage in my book. The file chooser in Opera is a crappy Windows 98 lookalike built out of QT widgets, but even that is preferable to Gnome's monstrosity of a file chooser dialog. I'm pretty sure you can change which file chooser Firefox uses if you're willing to screw around enough to do it, but it's nice to have a sensible functional default.
There are a lot of other little things that Opera does right, but I don't have the time or inclination to type about them all. On the other hand I have three main problems with Opera. One, it doesn't have the large selection of extensions that Firefox does. Opera has built-in abilities that give you most of what you'd want from most Firefox extensions, but there are a few gaps here and there. Adblocking based on regex matching of URLs for example. Opera does let you right-click a page and "Block Content", and then just click everything you want to block, which works well, but I don't know of a way to use some third-party auto-updating list of ad elements to block.
Two, it has some crap built-in that I don't want. It comes with a mail client, a bittorrent client, and a "widgets" tool and I don't know how to get rid of them. You can very easily IGNORE them however. You can set any external mail app (including terminal apps) to handle
mailto for example. You can also easily set apps to handle other protocols, which is typically nice of Opera to allow.
Three, I don't see an easy way to arrange which order the toolbars stack vertically. I'd like my tabs to appear directly above the web page content. You can get it to look about right by dragging all the individual buttons and toolbar elements from one toolbar to another and them removing them from the original toolbar, but that takes way too long. I'd like to be able to drag toolbars themselves around. I don't see why that should be so difficult. Firefox doesn't let you do this easily either, so oh well.
Those are minor concerns. In general Opera seems to be faster and more powerful and more configurable than Firefox. And it's cross-platform, and updates are released regularly, and it seems to be as standards-compliant as Firefox if not moreso. So why isn't Opera the most popular free browser for desktop users? It is closed source, and I'm sure that hurts it. Beyond that, not sure. Maybe people remember back when Opera was ad-infested unless you paid for it. That certainly still leaves a bad taste in my mouth. In any case, I'm going to keep trying Opera as my primary browser for a while.