What I do not like about firefox is something I see immediately. The home screen shows me a collection of links and images and rubbish that I would prefer not to see. This is clutter and I hate it. They say you can get rid of this "recommended by pocket" by changing a preference in the "New Tab Preferences" page. Actually it is even simpler than that. There is a tiny thing that looks like a gear at the upper right. The tooltip says this is "personalize new tab". Click this to get a settings dialog, turn off "recommended by Pocket" and you get a clean tidy browser.
The following are some ancient notes that may or may not have relevance.
Adventures in Computing / tom@mmto.org