Definitely depends on what configuration you want to run the light in. Sanyo eneloops (AA cells) and one of many possible decent multi-channel NIMH chargers will work great. The eneloops are slightly pricier than some other NIMH cells out there but have been proven to be solid performers that deliver trouble free service for hundreds of cycles.
If you are thinking about operating in 1xCR123 size configuration, a protected RCR123 from a reputable brand would be ideal. The AW brand cell is most commonly recommended. A DSD charger would be perfectly adequate if you are on 120V power. A Pila IBC is always a good investment if you think you'll be expanding your collection of li-ion powered flashlights.