I use vi by habit, and because it is always there ... I slightly prefer it over Emacs because it loads faster ...
But Emacs is just the best editor I'v ever used, if the the terminal is correctly setup with the keyboard on some situations , I remember once I was on a programming project,
all I had open on my X11 session was emacs, it handled :
a shell, actually a few, makefile's output, gdb's input and output and the sources of course
All the screens beeing used in the same time
by screen splits
I had no need to even open an xterm