The author of this well-written article ends up doing exactly what I did:
Switching (back) to Opera after a short-lived flirt with FireFox. I also switched to Maxthon after being frustrated for a time with Opera's GMail rendering (something they are working on).
But I can't do without Opera now that I've experienced how much better it magically makes images and fonts look, how much smoother the scrolling is, and all the little built in nick-nacks that are just plain cool (built in IRC client, RSS feeder, BitTorrent protocol).
In addition to Opera's compelling features, Firefox lost me with 1.5. Clearly the weight of OpenSores (f0dder's term) is coming down on the project, as you can see its move towards chaos. Please, no flames, I'm not here to debate this.
I think that any person who gives Opera a chance will become hooked on it as I have.
But getting people to give it a chance is another matter. Most people won't ever use anything but IE. Getting so many people to try Firefox was the result of an amazingly exuberant media blitz, the like of which may not ever happen again. But even with this amazing blitz, most people never tried Firefox, and fewer switched to it.
Opera needs to fix the few rendering issues it has with street-web, then somehow initiate a large media blitz. Perhaps millions in advertising is the only way. But then how are they going to make money? Beats me. They have some commercial interests in embedded and PDA environments, so maybe that'll save them.
Go Opera. You made a believer out of me.