Interestingly, I prefer vim to Emacs because of vim's tight shell integration. I feel like Emacs always try to reinvent the wheel, whereas vim plays much more nicely with the os shell. Just pipe arbitrary text through commands, outsource search to grep, building to make, etc. In fairness, I haven't learned Emacs yet, so maybe my impression of NIH is unfair.
And in most programs (especially vim) I'm only ever a C-z away from a shell I can use to test code, run curl, etc :)
It just makes more sense to me to host my text editor in my shell, not the other way around. But then, I guess Emacs isn't really a text editor so much as a development environment, complete with integrated shell.