One of the reasons that I chose vi over emacs was architectural. At a certain
level, vi was a text editor and emacs was an operating system, and since I was
running UNIX and was a UNIX philosophy person I just didn't want to be running
an operating system on top of an operating system just to do text editing.
I chose emacs because of muscle memory (Both the VAX and TOPS-20 machines at school had emacs as the default editor) and also because it lets me program better. I didn't let the fact it accomplished that by trying to be an OS or LISP-M or whatever get in the way of using the best tool for the job. In the 90s this meant that I had to be careful about the machines I used it on. These days, it just doesn't matter. Mostly, though, it was finger muscle memory :)
Warner