The Defender Infinity and Extreme from Nitecore are both some very cool lights. They both have the same interface, but feature different battery (Defender is AA, Extreme is CR123) and body types. Strobe is accessed by quickly loosening and tightening the head and the head loosened position is an adjustable brightness that you can set to exactly what you want. The Defender Infinity was my EDC for about a year, so I can personally vouch for its usefulness.

Here is a video of both lights: