1. The windowing. None of the editors/IDE's with full gui front ends handle windowing as well as vim (and emacs). Just this morning a was stuck in visual studio trying to track down an issue, swapping files everywhere and forgetting what I was trying to find by the time I got there. I opened up vim and could have it all in one screen, simplifying my mental load. It's also great for day to day things, like having a multiple views and a controller open at once in an MVC app.
2. Scriptability. Vim script is the php of editor languages, it's very easy to get started and/or write some quick and dirty scripts. Most of my day to day pain points are scripted behind a couple of key strokes. Also like php unfortunately, it's warts become noticeable on larger plugins.