Actually, Android TV boxes usually outperform built-in TV versions and they also get better support and updates. So if the TV you'd prefer is cheaper than the built-n AndroidTV, go for the cheaper one and get an external Android TV box.

No, the opposite is true. An external Android TV solution will give you better performance and longer support. The new Chromecast Ultra should be a really good option when it is released soon.

I have two Sony Android TVs and there are pros and cons to built in vs. separate. Compared to something like a shield, any builtin is going to be slower and more sluggish in comparison... but Android TV is Android TV so its primarily a responsiveness thing in the UI and viewing content should be similar. The biggest advantage is simplicity and integration with the Sony remote, without going through CEC or something. Overall, its not that big of a deal either way.

Depends on what you are planning to use the Android Os for. I had a sony android tv - swapped it for the samsung because i likes the colours on samsung more. And attached an android box - cause i use android box for way more things that the tv can offer. Plus - have in mind that the speed of the android box is way higher that the tv’s. But again - if you want android os just to be able to freely install some iptv app or smth - tv might be enough :)

Its nice to have ATV built into the TV, less wires and most 2020 models have nice performance.

Do your research on performance of the specific model you're looking at.

Samsung Rocks and they have all the major apps and keep them updated so you can't go wrong. They also support Apple Play if you are a Apple user as well.

I always recommend to people the #1 thing to look for in a TV is the Panel (picture quality). The smarts in the TV can be easily out performed and supported using a seperate box, I've had a number of friends who have purchased it for the "smarts" to find that it is sluggish or updates are not flowing through. So my advice to you is buy the TV for the panel, if you find a TV that you like look for the panel information and see if the panel is being used in other models that's cheaper- check out the model to see if a similar picture quality is available. If it is comparable, then buy the cheaper model, then buy a Nvidia Shield for your smarts for your Tv.

Does native Android TV built-in the TV has any advantage over something like Xiaomi Mi Box S?

Yes, and pretty much everyone who owns a separate Android TV device conveniently don't talks about this. These people are either blind or ... let's say, they have "problems"..

Build-in android TV has superior image quality over every external android TV device. Sony is a good example of this. The image processing (brighter, punchier colors) is better on the native OS on the Bravias. Native Android has control over the whole video playback/processing pipeline, applying different processing to the video or to the UI. This is not possible to the same extent when they get a digital signal through HDMI.

https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=d059f338-5cb6-11ea-b9b8-0edaf8f81e27

I use exactly the same image settings on the bravia and on HDMI 2 (Shield). If i use the same settings, why is the image looks different? The only possible reason is that the native playback gets some extra processing that is absent on the HDMI source.

This is just one example for this. Same youtube video played on the official youtube app.

Obviously if you don't have anything to compare it to, it's not that bad, but when you can, it's noticeable.

Personally when i watch movies i do it on the Bravia. But let's not forget the reason why i eventually bought a Shield. And that's software support. Sony stopped updating my TV any further, which was already a pretty slow device. Newer Bravias (G,H) has faster SoC, hopefully they get better software support. But that never will be as good as Nvidia's.

Buy the TV based on the TV quality not the TV OS. You can always add an Android TV device to the TV later if Tizen or Web OS are not to your liking.

No. I would stay as far away as I can from any smart features. I would make sure the TV works off line, and not pay extra for smart features. You also do want to make sure you get something with good rating from somewhere like rtings on picture quality, latency, and connectivity with the ports you need that support the resolution and fresh rates you want to use without excessive compression.