I wish I had caught this earlier. For set-top boxes is goes like this:
#1 AppleTV - it's hands down best of class. Fastest out of any of them and it gets the new services and features (atmos, DolbyVision (DV), etc) first for the streaming services. The apps on it also usually receive higher bit rates from the services than the other devices. Being in the apple ecosystem doesn't really matter for it since you're using the streaming services and don't have to rent from the Apple stores.
My main negative on it is that it doesn't support lossless Atmos for streaming home rips.
#2 nVidia Shield - Down at #2 but only by a hair. It does ATV's main negative so that's a plus. These days it'll handle most of what the streaming services throw at it but doesn't alway get the Atmos and DV streams. It also usually lags the ATV in getting the new features too which drops it to 2. The shields also has red push issue with some DV titles. It's a bit annoying when you run into one.
#3 everything else and the gulf isn't close. I don't know why anyone would settle for a FireStick, Roku, smart tv built-in, etc. None of them perform well due to lack of processing power. Their sluggish UIs and spotty support for the advanced features means they're paper weights at best.
Honorable mention: Zidoo Z9X - It's the best in home stream for a ripped collection. Amazing PQ and supports multiple DV profiles. It DOES NOT DO the streaming services though. It's only for in home streaming.
My setup has an ATV, Shield, and Zidoo in it. The zidoo is for all of my watching from my home server and the ATV is for pretty much everything else. The Shield mainly gets used if I run into an ATV issue and the TV in my Kitchen/great room only has a Shield which is mainly for watching YouTube while cooking.
If you guys ditch cable and go to OTA for games I'd highly recommend getting an HDHomeRun. I've been using one for football for almost a decade now and it should work great for the Suns once they're on broadcast tv (hopefully DBacks go that way too).
The HDHomeRun is a box that puts your OTA antenna onto your home network. You plug it into both the antenna and your network then it digitized the OTA signal so that you can watch it on anything in the house that has network connect. Then you can watch the games directly from your ATV or Shield.
Bonus on doing it is that OTA isn't delayed like Cox and DTV are. That lets you see the action first and gives you a snark advantage in the game day threads.