I agree with cy in that the best EDC light is indeed the one that you will always have with you, even when you don't expect to use it. In that light, I have carried a Photon (different models) for the last four years on my keyring (smaller than ARC AAA but just as useful). For in pants, where size really does matter, I have carried an ARC LS and then a ARC4. When the firefly came out, I started to carry one of them and it is still my EDC (FFII with 2 way switch). When I get my hands on a CR2 light, it will then take over for the firefly.
Obviously some folks have bigger pockets than mine to fill and can get away with carrying a small howitzer. But for me, and I think most folks, discretion is still necessary when it comes to an EDC.