if i have to used chromium than i will used Google Chrome. not Opera, not Vivaldi, not Yandex not anyone.

And yet you contradict this statement by using Pale Moon which is using Firefox's engine in Gecko, why not use Firefox instead?

Heck, Comodo maintains two browsers with two different rendering engines! Why not OP?

Because it requires Comodo little effort to maintain those two engines since they are open source being constantly maintained by two different groups. Presto on the other hand is a closed source engine that was maintained solely by Opera which was falling behind before they dropped it and would take very large effort to get back up to scratch.

What you don't seem to understand though is all those features you say you miss from the Presto-based Opera weren't actually a part of the Presto engine itself but rather the browser front-end that uses it, and such features would just as easily work with a different rendering engine in place such as Blink or Gecko which is what the Blink-based Vivaldi aims to do. If they so desired Opera could implement those features into their current Blink-based browser, the question is whether any of the features are actually worth their time and effort, personally the only features I'm still really missing that I'd love to see back are its session management and tab placement options (loved having them down the left side).