Fora quality single AA lamp , let me recommend either Zebralight H53c or H53w. Both use a single AA battery, Eneloops recommended.
http://www.zebralight.com/H53c-AA-Headlamp-Neutral-White-High-CRI_p_194.html#I have a similar model and also a headlamp powered by an 18650 battery, which is the best lighting appliance I have ever used/
Zebralight makes really good stuff....