Roku support and updates come from roku not the tv manufacturer.

Android TV because of Assistant and right now Android has 3 great options Xiaomi Mi Box 3, 3S and Shield TV. Prices from $60 to $190.

Roku is locked down and doesn't allow third party apps.

I've used both pretty extensively through a Shield TV and a Roku Ultra (the "top" option for each). It's going to sound odd, but I use Roku despite thinking AndroidTV is the better platform.

AndroidTV has a great interface that is focused around content rather than "channels." It multitasks well so leaving an app doesn't make you start over at the beginning. The Assistant voice search in excellent. The system is fast and responsive.

Roku is fine, but it's dated. It uses an old app-centric interface where your home screen is basically just a grid of apps. There is "global" voice search, but it's not nearly as robust. The results are based on Roku's database, not anything reported by the apps. This means you will not get results for YouTube videos and content that is part of an "add-on" (like shows that are available as part of the Hulu Live subscription) will not appear. There's no multitasking, and even searching using the voice search will kick you out of your current app and make you lose your place.

Despite loving my Shield TV I switched to Roku about a year ago, really just for the app support. I subscribe to Hulu Live, and the Android TV app was just updated to support Live TV and other new features at the end of July. That's two years after the service launched without an app update. I subscribe to Curiosity Stream, and at least as of a year ago there was no Android TV app that worked on the Shield TV.

Now, the flip side of that is that Android TV has Chromecast support built-in, and every service I use works with Chromecast. If you're okay with using that as a fallback, then you shouldn't run into any support issues. Though, if you're okay with Chromecast you could save yourself ~$130-150 and just buy a Chromecast instead.

Shield TV, no question whatsoever. There's a reason they haven't had to do much updating in 4 years, because it's far and away the best streaming box you can get. I should have started with it unstead of piddling away money on 4 different lesser streaming devices.

I don't think Roku's has web browser support, or IPTV support.

I have a 4K Roku TV, it's a great value, but I still use my Shield TV (Android 9.0) 100% of the time, it's just that good. Got everything setup so nicely on it.

If you are talking running an Android TV OS - on - a Smart TV then the only decent ATV to buy is the 2019 model Sony TV's with the much more powerful (vs any other TV running Android TV) - MediaTek Chipset in it, especially it's ripper GPU.

That snappy combo should last quite a while into the future now it finally has a decent Chipset under the hood.

It's exactly what Android TV running on a Smart TV should have been all along, all the previous Sony's with the older MediaTek Chipset were rubbish.

Anything else will date quickly as the Android TV OS becomes more demanding.

Otherwise pick a less demanding (& fast) OS like WebOS (LG) or Tizen (Samsung) - ie. something from the major Brands.

Be VERY careful if you want 4K HDR YouTube, do your research thoroughly for that App. As an example, you cannot get that from Youtube on a Nvidia Shield.

Just be aware you will get better picture quality from streaming Apps running on a decent Smart TV, if you watch a lot of non 4K content - because picture upscaling hardware is superior in modern 4K Smart TV vs cheaper external media players.

Avoid the Nvidia Shield if you want top class picture quality. It's old GPU is showing it's age these days vs the newer competition.

That is not what Shield owners want to hear but it's the truth.