good ones mentioned already by prev. Responders/Replies (currently own them all).
there is also the possibility of running some HL's on s 1xLi-ion cell, e.g. Streamlight Argo HP (a 2xCR123A powered HL) on 1x17670.
not to "beat a dead horse", so to speak, but i've found a number of 1 and 2 cell flashlights work well for "hands-free" lighting either clipped to a ballcap brim/visor, or head mounted using a JakStrap (original JS, or JS II). ok, still technically NOT a HL, but nicely functions as one.