I carry a Streamlight stylus 2-aa for the last ten years, when they broke down I returned them and they sent me newer models for free. lifetime warranty is a big thing in something you use every day.
That said my second favorite light is the Preon Penlight, I keep two of those for a discreet light like being out to dinner or flying and travel. The Preon P2 seems the most similar to my Streamlight and I own two penlight by Preon and they are great.