Apple TV 🤷
No ads, very little base level telemetry. Very good app support because of the large install base. I still run the first gen ATV 4k and just this latest tvOS version is the first update it didn’t get. Everything still works as normal.
Rumours say there’s a new one coming this month, but we’ll see.
If you are more of a hacker type, the Nvidia Shield is relatively ancient hardware wise but still top tier if you throw away the Google shit and spend some time with 3rd party tools.
And you can get 4k Chromecasts for like 19€ used, even the ones with the remote included.