I have to say, it's a very difficult choice.
I'm a big Opera fan, but due to their stubbornness not to improve the built-in adblocker, the questionable VPN and the lack of My Flow in the regular mobile version (?!) I've been slowly ditching it.
Firefox is that browser you want to love, but end up giving up - I dislike the battery drain on desktop and the painful mobile version (preview is faster, but lacks proper adblocking).
Chrome is just Chrome. The lack of adblocking in the mobile version is a big enough reason not to use it, not to mention the privacy concerns.
Chromium Edge is just a fast reliable browser with less Google clutter. No standout features, but I really enjoy the smooth scrolling and the back gesture inspired in the old Edge. The tracking protection seems to be inspired in the Firefox one (is it using Disconnect lists too?).
At the end, my current favorite has to be Chromium Edge.