From my personal experience SATIN BLACK is the best. I painted 2 wheels prior to my choice and matched them to my truck, I tried both Satin & Flat Black. The Flat black looked grey in certain lights and didn't have that full black look. It matched the tires perfectly due to being that kind of dull black/grey and it did not match my black truck. When I tried Satin, it was a no brainer. Gloss (IMO) looks cheap and a little tacky because it's too shiny. Makes the tyres stand out too much (being dull black/grey).
Do a search on here, when I choose it was an overwhelming Satin but I still wasn't sure so did a run of flat and Satin. Here is a photo at the very beginning of The Batram build. Rear = Flat. Front = Satin. The Flat matches the tire better but not the overall appearance and in different light and angles, Flat looks grey. Satin from any angle and any light always looks BLACK. It suits the truck better and enhances the overall appearance