Nobody mentioned Fenix LD15 yet??? It's way brighter than my E01 and just a little bigger than the AA batt it holds. It's small enough to be keychain worthy. It's a twisty and won't accidentally turn on. It has only two brightness modes. The high is actually too bright for most of my everyday uses. The construction is such that you can instantly feel it will be boringly reliable for years. It is just there and works.

One con for me is that it's not a "thrower" like the LD10 is. It's definitely a flood beam, but realize there is no way to get a respectable thrower out of such a short mirror.