Probably still a nvidia shield I think. OOTB dolby digital support IIRC, and a very extensive set of supported codecs for direct play.
If you're open to tinkering, it's relatively straightforward to get a similar setup going on a Windows or Linux computer with their HTPC app, which is much more affordable from a price perspective.
Along those lines, if you'd be using Linux for the HTPC app, there are some issues with the Flatpak intel VAAPI driver that cause stuttery playback on older systems. Disabling hardware decoding is usually an OK fix for this if you're just playing back 1080p content, otherwise 🔥hot take for 4K content it's easier to use Windows
Hmm interesting. Do you know if the Shield can play DTS-HD MA and Dolby TrueHD/MAT? My biggest issue currently is that my TV's inbuilt Plex app can't play these formats, so it's constantly transcoding.
I was seriously considering building an HTPC but I've heard that Windows doesn't play Dolby Vision files in non-native apps. Can you attest? In all likelihood I'm not a huge techie, so I'd probably stick with Windows anyways.
There would be way more options if more companies purchased all the Dolby licenses, but they're really stingy about it. Even the Nvidia Shield, which is commonly hailed as the best streaming device for its great library of native support, has limitations in that it can only play Dolby Vision profile 5 and most versions of profile 7. Those two profiles are the industry standard, though.
I've had mostly good experiences streaming Plex on the Shield so far, so I personally recommend it. ATV 4K is right up there too, except it requires the infuse app for lossless audio and it strips the spatial contents out of lossless audio formats.