vim is nice if a little painful.
I detest the vi editor. 
That is all.
ick, no, get vim, use vim. End of story, end of line.

For some reason, the commands and interface in vi seem needlessly complicated to me while vim seems so much more natural/intuitive.
On a related note, I'm basically learning iDL, C, and Fortran on the fly for my research.

(Switching back and forth is a pain, a painful, painful pain.)