Re: Opera...
A lot of browsers run on Google's 'Chromium' code (this is what Google Chrome uses). Opera used to run on its own engine called 'Presto' It is Chromium-based now though (blink engine), much like some other browsers that use the same code as a basis.
I'd say not to judge a browser without customising it a bit. The initial installation often doesn't present them in their best light. Appearance and ease of use can be changed. It won't be to everyone's taste but here's Chrome with bookmarks on the Bookmarks Toolbar and a dark theme added:
The screenshot is a bit small but it maybe shows that you don't have to accept the way Chrome is straight after installation. The same will apply to Opera.