I would like to hear which editors you guys use.
I started out with Notepad++ when i started coding for arma related stuff. Mainly because of the SQF highlight syntax of a community member.
Later i switched to Sublime Text 2 because it was on the hype train. Better design than Notepad++. SQF syntax highlighting by a community member. ( Sublime 3 is payed, so future doesn't look bright for free edition.)
Today i switched to Atom. It looks very promissing. You can download my Arma syntax package in the Settings section. Looks very customisable since it's open code.
For me git integration is really important. And that is where sublime fails for me. Atom is going in good direction with that. So i'm voting for Atom.

Screenshots:
Atom:

Sublime:


