I have several Olight Flashlight and I have been very satisfied.  The machining and build quality is excellent.  They use the latest CREE LEDs and Li-ION batteries.  They have very high capacity, they Operate at 3.7 volts, they are efficient, they last longer.  The flashlight manufactures tend to use the latest and greatest technology in their designs that use Li-ION batteries.  

There are two disadvantageous with Li-ION flashlights.  The batteries are expensive and You need to charge them.  The Olight flashlights all come with an individual magnetic charger that has a cord with a USB connection.  You can use any USB charging devise to charge the batteries.  Or, you can use a wall socket adapter for USB.  Or, you can use any of the many Li-ION chargers available.  I have a charger that will charge Li-ion, NiCd, NiMh, batteries including the 123,AAA,AA and Li-ION 18650, four batteries at a time.  But, it does need power to operate.

I am lucky to live in an area that our power is very reliable.  If power outages are a problem for you, maybe you should consider a generator in your plans.  Keep in mind that any battery will over time discharge sitting on the shelf in a flashlight or in a box.  That is due to the internal resistance of batteries.

Frank