Split screen done well would be a killer feature for me. Last time I looked Edge support was ok, but not great. But what kills Edge for me as a daily driver is the basic usability in managing bookmarks and tabs. It's stop and go for every basic operation like dragging objects while Firefox is simply a continuous flow. Firefox is invisible, Edge just gets in the way all the time.

Otherwise Edge is not bad at all. Chrome without MV2 is dead to me.