I've been using leds for the last year, and honestly I cant imagine going back. I bought a CMH just to see if the new HID could compare, it didn't.
The very best parts of going led are obviously the heat and power reduction, but also how close you can get to the plants and moreover how you can spred that light over a larger area rather than having a single hotspot.
For fixtures, it would depend on what way you wanted to go, I would stay away from COB lights as they act more like a single hotspot. If you want reliability and a company that stands behind their product, I suggest going with HLG or some other well known manufacturer that overcharges for their fixtures.
Personally I went with the more hands on approach.. you seem to like researching. I suggest looking in to quantum boards. I dont like the name either, sounds like a scam right away. But honestly, they can be hands down the absolute best lights you could have. By any measure.
They are now mostly using Samsung lm301b or lm301h leds. That are not shitting you 80% brighter than other LEDs on the market. Making your ppfd per watt insane, depending on how you build it. Basically hlg, spyder farms and all these other manufacturers are just building their own quantum boards and putting their name on them. But because you can build your own, you pay half the price or less and get way more options and the ability to build your own spectrum.
Search alibaba for "quantum board". They are great, fanless, robust, modular, cheap and can even be waterproof.
Hope I didn't just send you all down a rabbit hole lol.