So currently i'm using neovim. I have both it, and emacs, set up pretty extensively with configs from scratch and feel that i have a pretty good grasp of their strengths and weaknesses. But i'm moving from one to the other and back because something is always lacking.
Neovim is limited graphically by being a terminal application. Only one font size and one line hight can be limiting when working with more gui like concepts (popups, virtual text, overlays etc.).
Emacs does the GUI part great, but can feel sluggish in comparison. I'd really want to stick with emacs but every time i switch between it and a terminal i can feel it being slower. Not visibly so, but enough to be noticable.
So, when it comes down to it, that biggest relevant feature is, that both can be 100% programmed and customized to do what you want. Emacs even more so than neovim. But in both i can write my own functions to use and can, to an extend, change how the program itself behaves.
Are these two my only options, or is there something else out there that's a gui Editor and can be customized in a similar way?