Dolby Vision (HDR) or Dolby Atmos (sound effect)?

I see. I thought you're talking about  X85J TV and Dolby vision support. I have a lower end Hisense TV with Dolby Vision and I still enjoy it despite not gonna be bright enough to do so convincingly. It doesn't pop like Samsung but that doesn't mean there's no difference.

I did some comparison before settling for X90J. I even looked at X85J which is quite similar but it's just slightly less bright in hdr mode. X90J has FALD and newer XR image processing. Other than these, both are quite similar. I also looked at Samsung and then wonder why do you choose AU9000 over said Q60A? Price difference is not much and Q60A should be brighter with its dual led backlight. This is because you are considering X85J which should be priced between Q60A~Q80A.

My sister is working in Samsung TV dept but she isnt very knowledgeable in technical. She was told the older model is better too but was not told why. I also not sure since you cant really find much info on web.

If anything I can only suspect the panel. While doing research for X90J, I came across a couple youtubers that kept mentioning 2021 is the death of 4K QLED. They kept mentioning Samsung and even Sony switched their lower midrange from VA to ADS (aka IPS equivalent) panel. Samsung did it with QN85 series which is not cheap btw and certain sizes (namely 43") of X85J also uses ADS/IPS panel.

Tradeoff between both. VA has better contrast, while IPS has better viewing angle. Since reviews love to compare black levels, of course, prefer VA. My office just bought a 50" Samsung AU7000 for CCTV monitoring and truthfully, off angle really sucks. Washed out color and only can see a wall of bright light.