Can’t really speak on specifics of thermal, but as with anything, it depends on your use case.

The biggest downside of thermal is its lack of battery capacity and its lack of ability to pick out specific identifying features. But of course, its primary use is identifying living targets from long distances.

The biggest downside of night vision is the requirement of some form of ambient light, or an illuminator if there is none. However, it is significantly easier to use for navigation (hiking), especially in a binocular form factor. There is also no latency, as opposed to thermal which generally will have some form until you get to the really high end stuff.

The benefits of one complements the downsides of the other.

That’s about the extent of my thermal knowledge lol. If you want to see, and navigate, in the dark: go night vision. If you want to see targets way the fuck out there: thermal.

Depending on your budget, generally the best “starting” options if you are of the opinion of “buy once cry once” are either an expensive monocular or cheap binocular.

That said, I am not entirely a believer of that mindset as I like to frequently switch around what I do, and use my experience with one thing to decide where I wanna go next. This is a big benefit of night vision, as generally devices will hold their value decently.

Personally, I started out with a surplus Gen 3 PVS14 for ~1500 with no given specs. Given my time in the military, I knew it was going to have performance up to a certain level and some blems, but I was fine with that knowing I was using this as a stepping stone, probably keeping it as a loaner device, and likely going to upgrade as I learn more about how I personally use my device. As I got more involved, I decided binoculars might be better for my use case, which is primarily hiking on sloped terrain above all else, putting an emphasis on depth perception.

I ended up picking up a used Gen 3 ANVIS 9, which again, had no specs, but I knew (being surplus aviation NVG’s) would have certain minimum specs and probably significantly less blems.

Upgraded to a Chinese housing, BNVD 931’s, and now I have essentially my dream setup for the time being without getting ridiculously expensive. Only ~$4k into the ANVIS/BNVD setup total. You can, of course, get a lot more expensive.

I don’t personally find White Phosphorus to be all that it’s hemmed up to be, especially for the substantial increase in price. If you have the money to spare, why not, but getting lower spec WP is going to be inferior to getting higher spec GP for most people.

If you live in a spot where there’s usually a lot of ambient light, like a desert or somewhere with no tree cover, maybe you’d want to sacrifice some of the ability to see in extremely dark conditions for less eye fatigue (which is the primary benefit of WP vs GP).

The “diminishing returns” aren’t really there like they are for AR’s. As you spend more money, you are legitimately getting more capabilities and better specs. That’s just where the subjectivity comes into play as far as how much capability you need for the activities you do, or plan to do, and the environment you do them in.

Been a long day so I’m not sure how comprehensible this even is, but hopefully it helps a little!