Originally Posted by LDBetaGuy
I guess I'd have to say that DV is less consistent in its look. Sometimes its very dark vs. the HDR10 version. Perhaps it is intended to be that way and may be considered more "correct", but I don't prefer it. Also, at least on my system, the Roku is displaying all video with a somewhat different contrast or brightness or gamma (or some combination thereof) vs. my ATV4K. I just like how it looks. I go back and forth between the two streamers even though my original plan was to get rid of my Ultra.
I can't speak for Dolby Vision, since I don't have that capability, but I can speak for HDR10 vs SRD. At first I really didn't notice much of a consistent difference between the two so my initial thoughts were "HDR is pointless" until I started to study the same content in both formats with a better understanding of HDR, and what it's intended purpose is.
For me, I can say some HDR is darker then SDR, but I can understand why now, it's so the extremes don't get blown out like they can with SDR due to the limitation of the range and number of colors. The second main thing I noticed is HDR helps balance out extremes, so colors don't look, over saturated, or too intense. Incredibles 2, is my latest test, and you can certainly see the difference. Red especially is a big difference, in SDR, the red looks really hot, while in HDR, it's there and has a good presence but it's not exaggerated.
Depending on the movie, HDR also helps balance out low light scenes as well vs SDR content. I also have a few different devices I can compare content from. I have:
2017 Roku Ultra
2018 Sony X700
2017 4k Apple TV
to compare on a 2016 Sony 43X800D.
At this point, for the most part, they all look about the same for the same content.
I've also tested HLG from YouTube, as the TV supports it, the Roku, and Apple TV don't, but the Sony player does. That also has a nice look to it, from what I've seen.