While I'm mainly an emacs user, I do enjoy using mg from time to time. Especially nice that it comes with macOS nowadays (used to come with age old emacs version). I could probably do everything in mg, but I just cannot stand the auto indendantion in it when you have 8 spaces of indent and write a newline, the next line gets auto indented with a tab instead of 8 spaces (newline-and-indent assumes tabs are every eight characters..) Sure, this is not an issue if you use only tabs, but most projects just tend to be using spaces. Also, I think in OpenBSD mg there is a flag for enabling/disabling this (IIRC).

Nonetheless, I do like mg!