Batteries are more critical than the light itself in most cases. I'd go with lithium primary (non-rechargable) in a size that is easily found, so AA or AAA. If you want to go with rechargeable, go with good low self discharge HiMh or LiPo batteries, they all have pluses and minuses, but I'd suggest keeping at least a six month re-charge schedule, if not a 3 month. Also, many LED lights that have any sort of modes or memory have a slight vampire drain, so even your long-life batteries should be stored outside of the light. I use a lot of Aldi "Active Energy" batteries, and they do pretty well, have some older sanyo eneloops that are pretty good, I've heard good things about Ikea NiMh, and I just got some C and D size GP ReCyko batteries. The Cs are good hi-cap batteries, but just off the standard size, so my pelican saberlite doesn't hold them quite right, they need a shim. And the Ds are pretty much a AA in a spacer, but they seem to be good for my LED converted maglite which is sort of the power-outage light in the house. The GPs claim 80% after 2 years, so hopefully they do that, the trade off in NiMh is overall power vs. self discharge rate, so the lower cap batteries tend to sit for longer (price being equal)