I got into flashlights after Hurricane Sandy. I had a SureFire 6p from years ago and it worked great but I realized it wasn't enough for prolonged power outages. There's a TON of task specific lights and I just started ordering a bunch. I have 18650, CR123 (RCR123 LiFePo4), AA and AAA lights as well as rechargeable batteries and chargers to go with them. Being able to use the 18650's and chargers in my mods was a bonus.
I reach for my single CR123 lights the most often. They're usually 100-200lm which is more than enough for most tasks and they're small. The Olight S10 Baton has a magnet in the tailcap so it's very useful and one of my favorite lights. Olight came out with a few other lights similar to the S10. I have a Sunwayman V10R which has an infinitely adjusting magnetic ring. It's pretty cool but kinda gimmicky. Olight had a closeout on their T10 and T15 lights (single CR123 and AA) so I bought a few and gave the AA version to family since the batteries are easier and cheaper to find. I've also gave them ThruNite Ti keychain lights that use AAA and put out 80+lm.
I keep a 2x AA Olight T25 in my truck that replaced my MagLite 3x D cell. It's much brighter and smaller. I also have a
EagleTac P20a2 MkII that was on sale in a link someone posted. I paid full price ($75) and well worth it. It's on sale for 50% off ($37) which is a smokin' deal. It's my 2nd most often go-to light. I was really tempted to order another one at that price.
My 18650 lights are used when camping because I normally don't need 500-900lm but it's very useful when in rural areas and you need to light up a field

. I have 2 SureFire 6p (one is a Defender version) and I put some upgraded drop in LEDs to get them up to 900lm with 3 modes (low, med, high). I have a Olight M20 on my home defense weapon because the interface works for that task as well as a simple access side button for strobe.
These lights are so much better than the cheaper stuff from Walmart/HomeDepot/Lowes/etc. I'm a big fan of Olight, EagleTac and SureFire. Fenix seems to be a popular brand but the few that I had kinda sucked.