@jon I prefer @Waterfox . Why?

It allows to auto-hide bookmarks, tabs, browser arrows&update the page button each individually, etc.

Also, #Vuvaldi doesn't let's me to watch higher quality videos then 1440p.

#Firefox , #Librewolf , #Waterfox do allow me to watch **without buffering** (on my HD screen it buffers) 4K videos.

On mobile, I can set a custom search engine, specifically in Firefox and Waterfox, but you can't do it in Vivaldi for Android. Synchronization isn't comfortable solution.