I'm using GUI Emacs. There is one thing I use the mouse for: resizing windows. Apart from that, GUI is more visually pleasing, it doesn't try to emulate graphics by fitting characters into the grid. When it wants to paint a line, it paints a line, not a column of "|" characters; same with arrows and whatever. Another advantage is that it gets the key presses directly instead of through the terminal. In the terminal it can't distinguish between e.g. "C-/" and some other keys (I don't remember which).

However, I'm looking for a better editor anyway. Emacs is too unresponsive at times. I'll probably either switch to a GUI version of neovim when one of them gets good enough[1], or write myself a new editor, because I haven't really seen anything promising outside of neovim.

[1]: I think neovim folks might have abandoned this idea, so I'm not holding my breath.