I have WebOS on LG in the bedroom, Android on the Bravia in the living room, updated to the latest software.I'm not sure I get what people mean when they say that the future of TV is at arm's length and Apple is the closest to it.
Last year I bought my first 4K TV, and it was the first with built-in WiFi, a Samsung TV.
It has been amazing. It has cable/antenna of course, but all the other apps are built-in. I could instantly watch 4K HDR video from YouTube. The voice search on the remote is more accurate than Siri on my iPhone 7. It's a far better experience than using my old Apple TV (not the one with Siri Remote). The interface is very intuitive. I like it a lot.
When they were announcing the new Apple TV 4K, I saw the Apple evangelists like Horace Dediu tweeting live that 4K is the new big thing now. No, it's HDR! It's amazing. I thought he sounded like a Best Buy representative in 2007.
If you have a 4K TV, you already have almost everything that the Apple TV offers, with the exception of the iTunes Store. And what does the iTunes Store have that tons of other services don't?
The only thing I keep my old Apple TV connected for is mirroring my display on the TV.
WebOS and AndroidTV are crap excuses for TV software. I have traded them in for TVOS and can't wait for the 4K HDR to arrive.
What good is having 4K HDR capable TVs, when the software that runs the TV is as efficient as 1991 Windows computer.