From security perspective Firefox is not fast to adapt new technology. It took Firefox 5 years to implement low integrity rights. It took them a long time to move to a safer add-on environment. Mozilla's move to Rust programming language is really an advantage (compared to Chrome using C++), because Rust manages its own abstractions (meaning it is impossible to accidentally access a memory location that is outside the boundaries allocated and will be automatically de-allocated after use). Only on Vista/Windows7 Firefox would be my browser of choice in terms of security.I never used IE, Edge or Chrome. Because they were all shite. And still are. Google having absolute 100% monopoly with Chromium engine is their wet dream and we shouldn't allow it under any circumstances.
There is a difference between browser, render and java script. Chrome uses Chromium browser, Blink render engine and V8 Java script engine. Blink is a fork of WebKit engine (also used by Apple for Safari).
The chromium stable compiled version on Woolyss also offers a de-googled version. You can check that the 1-on-1 Chromium version is always earlier available as the de-googled version. Even the Chromium 1-on-1 is probably a better choice in terms of privacy than the Chrome browsers because it lacks the 'added features' of Google.
Opera and Yandex use Chromium. As far as I understand the info correctly Edge will not be using Chromium (like Yandex and Opera), but it will use Blink renderer and Java script V8 engine. Please correct me when wrong. So this would be like Mozilla was dropping the Servo (renderer) engine in favour of Blink.
When all browsers would use Blink and V8, the implementation of new standards by the W3C would probably be faster, so from this perspective the M$ engineer remarks contain some validity (not entirely because Apple should drop Webkit for Blink).