For lights, I am limiting the discussion to practical carry options: (to avoid writing a book)
Here is something to consider:
In a typical urban environment, indoor or outdoor, that you find yourself in, and you would be most likely to have an encounter in, when/where is it so dark that you cannot see well enough with natural vision to ID a threat? For me, I honestly can't think of anywhere that I have ever been within Lincoln city limits that would fit that discussion, although I'm sure if you look hard enough, there are places.
(Now, if you're like me, and you carry in very rural areas, and you are also thinking about coons with distemper, mountain lions, etc, then the discussion changes, but for now, lets limit the discussion to human threats and urban areas)
The big myth in white light is blinding/distracting an attacker. While you can blind or distract a person that you caught off guard, briefly, an actual attacker, a real threat, is not likely to be delayed much, if at all. And consider this: If someone is flooding you with white light, how hard is it to shoot or charge THE ONLY THING YOU CAN SEE? I have a mountain of evidence that it is not difficult at all, even in high stress, including a surefire that is permanently stained from probably close to 40 direct hits from UTMs and Simunitions from several different training events.
White light is only used to ID a threat (including purposes of engaging). That is its only practical proven use against an actual threat.
This same point is one of the reasons to not use a weapon mounted light. A handheld can be dropped, held out away from you, etc to lessen the chances of you receiving a lethal dose of lead. You can also use the light to see, without pointing your weapon at everything and everybody.
The advantage of a weapon mounted light is quick accessibility, and the ability to maintain a two hand grip on the weapon. Now... what distance to CC encounters tend to happen? Is the latter really that valuable? And with the point at the beginning of the post, is the former really that valuable?
These are questions that only you can answer. I have no idea on the specifics of your situation/environment. Just meaning to give folks some things to think about in their equipment selection.
Get trained and keep practicing, on whatever light system you choose. Make spotting/painting and displacing an ingrained habit, that you do automatically.
Now, in the off chance I am carrying my LC9 (without a light), and I do find myself in needing white light to ID a threat, I do have a backup: My phone. A reasonably bright LED flashlight is built into most modern smartphones. I have practiced a few times with this, and while it takes me a couple seconds to get the phone out and the light on, it is a valid backup option, should I need to ID a threat in near total darkness. It is by no means ideal, especially with the backlighting on me from the screen, but better than nothing should I need to illuminate a situation.
