Whenever I open certain websites (Google, My banking sites etc...) it decides to load a basic version of the site (Similar to the ones I used to see in Opera Mini on a Java Keypad phone). Maybe it is the website's fault, because I'm pretty sure Firefox is capable of displaying the full website, but as an end user, those pages are broken for me. Hence using Brave.
Vivaldi if you want a chromium privacy experience. Not fully open source but works well, has desktop sync and a good tablet UI which is my biggest reason for not using FF.
I only have a tablet and a phone and until FF creates a viable tablet UI I'm staying away.
Vivaldi is not a "privacy" experience. It sure has some comfy features, but Vivaldi is not private. Use it if you like it's UI features, just know that it isn't private.