I know most of the answers here, prefer Gecko over Chromium because Google is a monopoly, but honestly I would like to make the switch, the bad thing is that I still find the Firefox interface on Android old, I know it seems a bit silly to risk a little privacy for a comfortable and visually pleasing interface, but recently I saw that Chromium forks are even more secure than those using Gecko, that's why I still use Cromite

I take this opportunity to say that possibly the solution to this is WebLibre, a browser based on Gecko which is exactly what I'm looking for, unfortunately still in alpha but from what I've seen it's on the right track