Recs.
Updated
SpecsUpdate
Pros
Pro Lots of built-in features that need to be installed as plugins in other browsers
Opera has a lot of built in features by default which are found only as plugins in other browsers. Some of these features include: RSS client, free and unlimited VPN and Ad Block.
It also has an automatic currency converter. And when you mark some text on a website you don't need to right-click to search for it. After you have marked the word(s), a little window comes up with some options for 'Search' or 'Copy', you just have to click.
Pro Opera can have extensions from Opera Addons & Chrome Store websites
Opera supports cross-browser extensions. Opera Addons site keeps quality up compared to Chrome Store. Full of useful extensions, Opera also supports extra APIs like Speed Dial API, Extension Sidebar API and Stash API meaning wider variety of extension possibilities than in Chrome.
Pro Lots of new features in Opera 2017 & 2018
Opera got Reborn UI as the first implementation from Opera Neon concept browser. Snap -feature is next. Opera constantly improves its basic functionality - unlike Chrome.
Cons
Con Proprietary
While Opera is currently available gratis (without monetary charge), it is currently not libre (meaning that it does not allow users to view the source code used to create, to modify that code, or to redistribute modifications) and is therefore neither free nor open-source software.
Con WebKit/Blink is not customisable or lightweight
Opera is built on WebKit/Blink, which means it shares cons of Chromium: high RAM usage (Not lightweight), lack of customizability.
Con Just a Chromium clone
The beauty that was Opera on desktop ceased after version 12, now it's a Chromium clone with a focus on not being different or unique in any way.
Opera 12 is still available, but should be considered obsolete as it doesn't support standard web security measures anymore.
Recommendations
Comments
Flagged Pros + Cons
Con Owned by a Chinese consortium
Who certainly need to conform with Chinese government requirements to let them infiltrate everything you do online.
Pro Opera Turbo
Opera has a functionality called Turbo which increases browsers speed and reduces data consumption considerably by compressing the data that's found in a web page.
Pro Plenty of extensions
Can use extenions both from Opera Addons & Chrome Web Store.