I'd been using Opera, since the 90's when there used to be banners. Like I was a big fan of Opera since, as @cfpt pointed, it was awesome. I recently switched to Chromium and eventually to Chrome. Few reasons:
Both Chrome/Chromium and Opera now use the webkit browser underneath the hood so the rendering time of the pages are just the same.
As a developer compared to Opera DragonFly, Google Developer tools are easier to use and more importantly loads faster. I'm writing in reference to Opera 20.
I often travel to rural areas in Asia as a part of my work where 256 Kbps internet is a luxury. At such times, the author-mode and no-image mode used to be lifesavers along with the turbo-boost. Opera 20 doesn't have those customizations available anymore.