Are you talking about games as well?
For non-game apps, my most used apps are:
1. Coubicle TV - Simple app that plays video memes and funny clips from Coub.com. It was made by user
@rshev and is often on in the background on my TVs. It is free.
Download Coubicle TV by Roman Shevtsov on the App Store. See screenshots, ratings and reviews, user tips and more games like Coubicle TV.
apps.apple.com
2. YouTube - Don't think I need to explain this one. The tvOS version of the app could be better. Actually the old ATV2 and ATV3 version of YouTube app is a lot better in many ways. That said, my family uses it a lot.
Download YouTube TV by Google on the App Store. See screenshots, ratings and reviews, user tips, and more games like YouTube TV.
apps.apple.com
3. Plex - They are adding features to Plex all the time, and with the new Beta server SW that might be out soon, it will allow a single source search for all content within Plex, as well as all the streaming apps out there. Making searching for something faster and seeing the options there are to watch it, whether it be free, something you have to pay for, and/or something you are currently paying for. You can add the searched content to your Plex watch list, and watch it when you are ready.
Download Plex: Stream Live TV Channels by Plex Inc. on the App Store. See screenshots, ratings and reviews, user tips, and more games like Plex: Stream Live TV…
apps.apple.com
4. Netflix - The content has really gone down hill since 2016ish. Somehow Netflix (and others) forgot how to make good stuff, and just thought checking boxes would be enough to satisfy their consumers, but people have had enough of it. With the recent announcements of cancelled shows, it appears that maybe Netflix might be getting back to making less content overall, but sticking with stuff that is good quality, all while cancelling the goofy shows that hardly anyone watched. The App sucks, but this is the same for Netflix on every device now. Actually, this is another example of how the older ATV2 and ATV3 version of apps is better than what is on current devices.
Download Netflix by Netflix, Inc. on the App Store. See screenshots, ratings and reviews, user tips, and more games like Netflix.
apps.apple.com
5. Prime Video - A good mix of content, but the app UI sucks. Jack Reacher and Terminal List are two good shows that were recently released.
Download Amazon Prime Video by AMZN Mobile LLC on the App Store. See screenshots, ratings and reviews, user tips, and more games like Amazon Prime Video.
apps.apple.com
6. Disney Plus - Better UI than most other streamers. Popular with my kids, but I don't watch it that much.
Disney+ is the streaming home of your favorite stories. With thousands of hours of entertainment from Disney, Pixar, Marvel, Star Wars, and National Geographic, there's always something to explore. Stream the latest movie releases, exclusive Original series, and a catalog of classics with more...
apps.apple.com
7. iCloud Photos - Not sure where to rank this one, as it is used often. Nice to watch all the photos and videos of my family throughout the years.
Use the Photos app on Apple TV 4K to view your iCloud Photos, Shared Albums, and Photo Memories.
support.apple.com
8. Music - Listening to my music from my iTunes library.
In the Library screen of the Music app on Apple TV 4K, find content you added or purchased and music synced from your computer.
support.apple.com
9. Pandora - The app has issues. Not sure if I am the only one, but to get the list of my recently played stations, I have to open the app, then forced close it, then reopen it. Other than that, it is good.
Download Pandora: Music & Podcasts by Pandora Media, LLC on the App Store. See screenshots, ratings and reviews, user tips, and more games like Pandora: Music &…
apps.apple.com
There are some others, such as utility apps, background video and photo apps, streaming apps, and others, but the above are the ones I use most. Maybe I am forgetting some other ones that I use often. I will think about it.
Let me know if you want to know about games.