I saw this post by guy named Jay Landoe. I am just pasting it here for the info:
I see many people asking about weaponlights, trying to wade through the many options and price points and performance metrics, often being bombarded by single sample size testimonials of overhyped underperforming options, and I felt it necessary to distill down the data to a few easily understood, readily verifiable bullet points. Keep in mind, these are data points established through my own experience and evaluation of different light options over the years in the military and as a motivated civilian defensive shooter, as well as data collected from vetted professionals with far more knowledge and experience than myself.
Before we get into the list, I think it is important to give a quick explanation of the difference between lumens and candela. Lumens is the raw output of a light source, the total amount of light that it emits. Candela is a measurement of a light's ability to focus that light into a specific space. Think of lumens like horsepower, and candela like horsepower at the wheel. It doesn't really matter how much horsepower you have if you can't get that power to the wheel efficiently. The reason candela is so important when measuring light performance is because weaponlights need to be able to concentrate their light on a target to give the shooter as much information about the target as possible while preventing the target from getting any valuable visual information of their own. A 100 watt light bulb is rated at 1800 lumens, but only around 135 candela, so you would never want one as a weaponlight because it has no focus of that light. So when you see the different candela ratings in this article, this is why they are so important.
This is going to be a bit of a read, so settle in. And if you want the nitty gritty without the minutia, skip down to "TLDR".
Here is the list:
Modlite, while a relative newcomer to the industry, has really upset the marketplace with their highly modular and mission focused configurable solutions. The OKW is currently at the top of the list as far as pure output performance is concerned, with a staggering 69,000 candela, 680 lumen output providing clear PID out to 200m+ or eye searing optical plane denial at CQB distances, while the PLHv2, rated at 1350 lumens and 55,000 candela, provides a wider spill and higher raw lumen output at the expense of candela, making it a very effective option for team members looking for wide flood to aid in clearing unfamiliar environments and for general purpose defensive carbine applications.
Modlite has more options for mission specific application than anyone else, from wide flood to light saber hotspot, warm or cool light temperature, two levels of IR output, as well as long and short bodies, all capable of being mixed and matched to fit every possible requirement, all compatible with the venerated Surefire tape switches and mounts, Unity Tactical TAPS switches, and with a growing aftermarket with companies like Valhalla Tactical, Reptilia Corp, all creating new solutions to even more configuration requirements. Modlite has also recently collaborated with Unity Tactical in creating the ModButton, an integrated user configurable mount and tape switch providing improved efficiency for maximizing light output.
That being said, they're also well into the $400-500 price range when mounting solutions, endcaps, and tapeswitches are added to the price tag, which may put them outside the budget for many shooters.