"Smart"TVs: (with or without AirPlay/HomeKit) (vs TV)
A number of questions may arise when shopping for new TVs: Do I need an TV if I have a SmartTV? Should I buy a new TV with AirPlay? Should my new TV have HomeKit?
Here are a couple of quick things you should know regarding support for Apple services right off the bat:
Smart TVs can have three different "levels" of support for Apple's services (and having one feature doesn't mean you have the other features):
HomeKit: ability to use basic functions (on/off and input select) in HomeKit scenes and automations
AirPlay: ability to use the TV as an AirPlay speaker in HomeKit scenes and automations
TV+: has an TV+ app built into the TV to watch TV+ content without an actual TV
A SmartTV with HomeKit or TV+ support cannot be a HomeKit hub like a traditional TV.
While the above features are, what, "neat"?, and might be useful, for me they are not blow away features that I just have to have. For me, when shopping for a TV, the picture quality of that TV is of primary importance. Everything else is secondary. You might have some budget, space, and "design" priorities to consider as well, but image quality is king. Smart features, would be the absolutely last priority I would consider on any list of TV features, whether those smart features are HomeKit support, or simply traditional "smart" features like a built-in NetFlix app.
Here's why I place so little value in the "smart" features of my televisions:
Television Interface: Even when watching "TV", I am not using the manufacturer's hideous user interface, I am simply watching TiVo or the TV, so the UI and UI performance of the TV software is of little concern to me.
Audio Quality: I can always enhance the audio of my TV with external speakers (and who wants to AirPlay music to crappy TV speakers in the first place?).
HomeKit/AirPlay Support: An TV is going to have by far the best HomeKit support regarding features and reliability. It will also act as a HomeKit hub, and Bluetooth repeater. Not to mention the HomeKit support built into a television is likely to be buggy, and probably lag behind Apple's software updates.
App Experience: The TV is also more likely to have better app support in general, for things like NetFlix, Amazon Prime, etc. The software and hardware on TV's usually doesn't come close to the AppleTV. Usually the software is poorly written, and the hardware makes the software run slow.
Consistent User Interface: Often times, the apps on your TV are written by different (usually temporary, contracted) developers so the interface between all of the apps is inconsistent and poorly written. The same can sort of be true on TV, but generally speaking, the UI paradigms are much more similar and the performance and quality is more consistent.
Long Term Software Support: Which do you think is going to be updated more frequently - the NetFlix app on the TV, or the NetFlix app on the LG 92JHG9876JHG/3 TV? How quickly (if ever) is your TV manufacturer going to update HomeKit support for iOS 10.14, iOS 10.15? How buggy do you think it is going to be?
Privacy: Smart TVs track EVERYTHING you do. You might even want to consider keeping your TV disconnected from your home network. You can always temporarily connect it as needed to check for firmware updates and then disconnect it again.
Upgrades: Finally, when you do need to update the "smarts" of your TV, simply buy a new TV.
Also, don't rely on HDMI-CEC to control the power state of your TV. When it works it can be nice, but it is a finicky beast that often does not work (and a simple firmware update can often break one that was working). I have even had devices from the same manufacturer that didn't do CEC correctly. So if it works for you, great, just don't count on it or make a purchasing decision based on it.
A quality screen is all you need in a good TV, and should be the primary motivator in your purchase decision.