My 2 cents worth: I am over 70 years old, and have a flashlight aficionado for about 50 years. For about 20 years, I was active in helping lots of LEOs obtain, upgrade or maintain their lights. It has been very funny over the years to hear stories of my officers being asked to go over to another cop's call because of their flashlight.
this thread describes one such light from many years ago:
https://www.candlepowerforums.com/threads/the-story-of-a-hero-cop-and-his-flashlight.482601/
Over the decades I have owned or maintained many hundreds (maybe thousands) of lights of many many types and makers. Some ideas to keep in mind while selecting.
1. Pick a light that takes 18650 batteries. For lots of reasons.
2. KISS. The fewer levels the better.
3. Try to avoid any company that does not REALLY have a no questions asked lifetime warrantee. That basically means, buy American Made. Surefire and Malkoff have always been totally outstanding in honoring their lights. Unfortunately, I have not had a single China made light that either had no warrantee, or for which it was a huge hassle (send back to China on your dime, and we will see. You may hear back, or maybe not, within several months.) And, yes, that includes some American run companies who have their lights made in China. Now, some of the new companies, like PowerTac, I have not had experience with.
4. Verify that your department approves the specific light, if required.
5. Really think about how you will be carrying and using your light. Lots of officers just prefer to use an armpit hold for many light uses, like writing tickets. So, a two 18650 might be most useable in the long run.
6. Don't get too attached to turn-on lumen or candela output. Look rather at the actual out put over the first 3-5 minutes.
7. Consider having a smaller light for admin or close duties, and a larger one for search or other purposes. This is in addition to a small keychain light: A Surefire Titan Plus has served me and many others without fail since they were first released.
8. Avoid electronic switching and stick with mechanical switching lights. The old Surefire 6p or Malkoff M series are perfect examples.
Here are my recommendations:
For a single light: Surefire Fury Intellibeam, Cloud Defensive EDC DF, or Malkoff MD2 with M61 SHO and hi-low switch.
My personal favorite two light configuration: Surefire E2T MV Tactician and a Malkoff MD4 Hound Dog. The Tactician has very similar output with Obtronics 16650 batteries compared to primaries. And the MD4 with two of Obtronic's best 18650s gives fantastic solid long range and long term performance.
A note about the Intellibeam: I was very suspicious about the sensor when they first came out. But, after many years of use, I and others have never had a failure, and the actual light output at the low level is super practical at all normal distances.