Many years ago, in the early days of the internet, Microsoft had the idea that they would dominate and control Net development by leading it. Specifically, by making Internet Explorer standards deliberately different from all the other browsers, as well as making IE a mandatory part of Windows. The idea was that if they could capture a majority of web content providers to compliance with IE, they could eliminate competing browsers. One can speculate about what their game plan was to be, once they'd achieved complete dominance.
It didn't work out, fortunately.
But the residue remains, in terms of IE being impossible to expunge from Windows, and IE still having extremely poor conformance to W3 html/CSS standards. As everyone knows who codes html/css and sees the many notes about IE incompatibility, as well as the many website page sources that include code to detect IE clients and perform contortions to make the code work for that client.
If IE was so great, why did Microsoft abandon it and start virtually from scratch with Edge?
(Or, another possible interpretation could be that IE wasn't easy to adapt to whatever underhanded user-surveillance facilities MS wanted in the browser, to work hand in hand with the known nasty crap buried in Win10.)
For those who don't believe MS wanted to rule the Internet, did you know that at one stage the Australian government was in discussions with Microsoft, to have MS provide *all* Internet access to Australia, via MS-owned servers in the USA? Thank God that nightmare didn't eventuate.
As for Opera, it *used* to be great, till they dropped their own engine and replaced it with the Chrome engine. Which I totally don't trust. I still use the last pre-chrome Opera version for local development (it's very fast and nicely customizable) but it's too old to work with many online sites now. (Still works with eevblog!)
At least Firefox has a Portable Install version available, so that's my primary online browser these days.