Things I benefit from:
Apple Ecosystem: easy to input text using your phone rather than on screen keyboard. One underrated feature is airpods. The spatial feature when using them is very very good.
Speed: It's the fastest TV box/streaming device out there. Snappy and responsive. I have a Shield and I love it but only yesterday it crashed on an app and rebooted itself.
Codec support: I'm a heavy Plex user and via the device itself and an app called Infuse I consider it the best Plex experience regarding its UI and it flawlessly plays everything I have on my home server. Ethernet connection is also important to be, something a lot of streamer sticks tend to omit these days.
Mic: I personally think it has a pretty decent mic and voice assistant. I've had experience with the Shield (google) and Fire sticks (Alexa) and I never used their mics because they could never recognise what I was trying to say. The Siri remote is fantastic. I don't use Siri in day to day life but on the Apple TV Siri does its job well compared to others.
It can do a lot more. It has a bit of a gaming ecosystem but you need to pair a controller for that, but that could be useful in a pinch. You can game stream to your TV with apps like Steam Link or Moonlight from your PC. The app support is pretty good, all the streaming services are well supported here.
Negatives: If you are a home theater nut with an expensive surround sound setup, the Apple TV 4K does not support lossless surround sound. Also, you cannot sideload apps on it, or at least you cannot do so easily. Android TV wins out by a mile if sideloading is your jam. Android TV has some great sideload apps like Smart Tube Next and SoundTV as just some examples.