If you spend the dollars on this expensive audio/video then you should make sure to get your money's worth with content:

1. UHD Bluray. Yes you need a new player for this and these disks are still the highest quality with best uncompressed video. So it is still worthwhile to buy them.Ironically, the best choice is actually to get a $600 Xbox Series X since it has a UHD bluray thrown in for free although controlling it is really a pain. But if you want a dedicated player then the Panasonic DP-UB9000 is crazy expensive at$1K but does have HDR, Atmos and DTS:X. The more modest Sony UBP-X1100ES is \$600 and also has HDR10, Dolby Vision and Atmos and DTS:X. They are streaming at 80-100Mbps so as you can imagine the image quality is way better. The files are 80-100GB to give you a sense of how big the uncompressed movies are. Even so, these are really niche products.
2. Netflix 4K. Ok, the streaming services don't look as good as raw UHD Blu-ray, but they aren't half bad if you have enough bandwidth. While the content is limited when combined with Atmos, it is pretty crazy good. The Old Guard is one good example and HD-Report keeps a regular list. I find just a search for 4K is great. The best thing about Netflix is that they have clients for everything. From LG TVs to Windows to Mac to mobile phones. The LG TV version works really well running on WEbOS and delivers HDR and Atmos. so does Windows. And Chef's Table looks incredible. They normally stream at 15Mbps but during Covid, they cut it to 7Mbps.