A big +1 to RA Clicky suggestion! I have a handful of Novatac lights and an RA Twisty and they are VERY versatile beasts. I EDC two Novatacs daily (see the links in my tag line below). I also have a Surefire E2L because it will run on a 17670 if the body is bored a little bit and you still get great runtime. I've been tempted at times to pick up a cheap e1b from the marketplace but I know it would just get relegated to my wife's purse after a while. The inability to run on a rechargeable has really steared me clear of it to date.
Let us know what you end up doing.