I'd vote for vi as well. Emacs might be popular, but I find its commands not as easy to rem, as they are on vi.

My personal useage, is usually across the network. I use vim to configure systems many miles away. I can simply SSH into a box, load vi, edit configuration files and I also use it to collaborate with an Author friend, while she writes her novels. We add in the Vim/Latex plug-ins, and I edit the books as if they were local.
Vim with all the available plug-ins, filters add alot more power to this tiny app.
Learning the commands are simple, and they make sense.
Once you learn vi/vim you'll soon be executing vi/vim commands in your GUI editors by habit, and you'll find it much more powerful in certain aspects, than other editors.