Whether camping, prepping, or hiking, a good flashlight is a necessity. I have several....a small Mag-Light on my fanny pack, and angled one with changeable colored lenses and a few other backups. They all use "AA" batteries, of which I have extra, that I rotate the shelf life of.
So far I have resisted one of those "Kinetic" shaking flashlights...they just seem too noisy to me. but will probably get one anyway. I'm pretty sure LED is a good idea, all mine have krypton bulbs (yeah I have extras).
They make Solar Powered flashlights and other solar lighting. These would be excellent for your retreat or backup. My emergency radio has "AA" batteries, a crank charger & solar. For $79, you can get one with a USB port to charge your electronics! (Need a larger Solar Panel for that too).
Not sure if you need to protect flashlights or solar powered items from EMP...sounds logical to do so...but that's another subject.
I forgot about "Lightsticks"...I'd just get white, about 99 cents each. Get at least a dozen!
When the SHTF, you do not want to be left in the dark!