Main thing that's keeping me right now is copy select with mouse that stays in pane. Tmux would always cross horizontal panes so I'd have to zoom the current pane, alt + mouse select, then unzoom. Zellij I just drag over what I want and release the mouse button. I do however miss using the mouse for pane resizing though.
I tried Zellij and couldn’t get the Alt key to work on mac. And then when ssh’ing into a server I couldn’t see some of the icons because it required a special patched font.