I kinda like the idea of a two-panel file manager, and have tried them all. Not one of them was capable to replicate the power, speed and extensibility of Far Manager, which only fault is that it's windows only.
Fman could be the one if only it was text-based. GUI just ruin it. It automatically means that it won't work from the shell, and it's a deal breaker, that's why I have to continue using mc, despite it's glaring inferiority to Far.
One of my biggest issues with terminal based file managers like Ranger or nnn (https://github.com/jarun/nnn), is that it's not immediately clear which files I'm currently looking at, since it's all text-based (duh!).
But I loved the extensibility and keyboard driven nature of the terminal-based file manager. That's something which other GUI-based filemanagers are lacking in that, except fman.
Far Manager looks interesting to me, since it seems to be allowed extensively customized too. Will give a try soon.