Quoted:
You give me way too much credit raf, I'm just really experienced at screwing up and trying to learn from my mistakes...oh, and posting my AARs here

You bring up some good points.  I typically like to avoid the separate battery-pack lights...mostly because they're bulky and often best used for serious/extended night or caving use.  I would still recommend the angled lights (Armytek, Zebra, etc.) for use with a hat.  I can get them to work on a helmet or ball cap (although the angle of light won't be right at your feet with a larger bill).  Just for simplicity, the single bands work well for me and I usually take the top support straps off unless it's a really heavy light (like the Fenix HL60).

As long as your light is IPX8 (IP68 is the highest rated lights I've heard of) rated, it's going to be waterproof for anything except doing scuba or diving.

I like simple UI selections.  I hate having to cycle to where I last left the light and is one reason I really like the ArmyTek models.  You can start with a fire-fly mode (something like 0.15 lumen) and cycle up and the last mode you left it on, that is what it will turn on with (unless you press and hold for the lowest firefly output).  It's less a "tactical" sun-scorcher and more utility, but that's what I prefer in a headlamp and often run less than 50-60 lumen for most tasks.  At my "seasoned" age, I still have to get up once or twice a night to answer a call from mother nature...I use the ArmyTek on the 1.5 lumen mode as I have to walk about 30 yards outside the building over rocks (and right now in the snow) to use the bathroom.  My headlamp gets used a lot

Having a lock-out option is also important, even if it's a just a cap rotation (as long as it doesn't jeopardize it's waterproofing); some have a simple UI way to set a lock-out which is also a good option.  What you don't want is your light getting activated in your pack (and higher output models will actually burn a hole in your pack).

I'm with raf on getting any of the bigger lights that are strictly rechargeable.  I know they're a little less efficient (maybe not), but there are several magnetic charging options for 18650, 18350, or 14500 batteries.  I typically avoid the mini-USB rechargeable lights; it's just one additional point of potential failure.  I'm okay with the option, but an outdoors light is (IMHO) best used with a replaceable spare battery, and if the battery can be recharged inside the light, I would prefer a magnetic charger.  Even with most of our backpacking, I carry a small AC USB charger and simply love this universal magnetic charger as it will charge just about any battery:

https://www.batteries.gr/media/catalog/product/cache/2/image/1200x1200/f6e26b16170e5b1d9a8c9c2a6f52e5aa/m/a/magnetic-charger-battery-olight-uc-8-750x750_1.jpg

Ultimately, many of the decisions come down to the battery choice.  I love the CR2032 Petzl e+LITE, but not as a primary, yet I almost always carry it as a backup.  I use the Zebra 14500/AA headlamp for backpacking, only because it's the lightest headlamp I've found with the minimum features I like, and I can use regular Lithium batteries (which are lighter than either 14500 or Ene-Loop batteries).  If I had to pick one light to cover most of my needs for extended periods, I would choose my ArmyTek Wizard in 18650.  Everybody has their favorite LED brands, and what typically separates likes from dislikes are the smaller features such as preferred UI, output levels, and battery preferences.  I do like the Fenix HL50 as it's a solid light and can use with AA or CR123.  I only wish it was rated to take the higher voltage 14500 or 18350 batteries.  For a "tactical light", I also have the Streamlight Sidewinder Compact as it has red and IR, but it can also take AAA, AA or CR123 batteries.  For me, I've just found Zebra, Fenix, and ArmyTek as my preferred brands for headlamps (single battery).  Here's what I have with me in Afghanistan:

http://img.photobucket.com/albums/v440/ROCK-6/Flashlights%20Electronics/20171020_122603_zpsuw1yxt61.jpg

There are just so many options and choices and they change almost monthly.  From my recent experience, if I was starting over, I would go take a look at ArmyTek.  A guy from another forum turned me on to them, and I now have two and they are just reliable performers with a simple UI, great features, and a robust design.  I have had an issue with a couple Zebra lights (both sent back and fixed, but shipping took them out of play for over a couple months).  I've never had problems with Fenix, Olight, Nitecore, Sunwayman, or FourSevens.  Options are good, but it does take a while to find out what you really like and getting a product that performs with the features you really prefer.

ROCK6

Quoted:
@raf, yeah, the caddies are really just open storage options needing a waterproof bag if outdoors.

One of the reasons I like the single-cell lights is that that the Delrin tubes are perfect for carrying a single, extra battery.  This is my top choice for carrying a spare battery when backpacking.  Another great option (although admittedly more expensive) for "tactical" applications, are the Thyrm CellVaults: Thyrm.

http://img.photobucket.com/albums/v440/ROCK-6/Flashlights%20Electronics/20180826_111752_zpsdol9t4zt.jpg

These are pretty handy for carrying AA, CR123, AAA, or even 18650 batteries with a very handy attachment to gear, waterproof, and easy to access.

The older Surefire storage unit is still going strong for CR123 batteries.  Also, if storing batteries in a waterproof bag, the silicone protectors just keep the terminals from getting damaged or batteries shorting-out if they make contact.

ROCK6