I do both. I love my SHIELD but the YouTube app for AndroidTV sucks, and I'd generally rather cast. I've got a Vizio SmartCast that's been very good with 4k. I do cast over Ethernet though.
I have a 4k TV but I don't even try to use the built in apps on the TV. The Shield is going to get more updates and should be a better experience than any TV can hope to have.
I would never recommend connecting a "smart" TV to the internet. They are pretty consistently underpowered, you are lucky if you get security updates much less feature updates, and I just don't trust those manufacturers to responsibly handle my data.
From what source? My LG streams 4K Netflix and YouTube just fine. Downloaded stuff doesn't seem to work with any of my devices, as either my network or my hard drive can't seem to keep up.
My LG TV from a couple of years ago streams 4k from Netflix and YouTube without any problems. I used to have it hardwired to my router but after I upgraded my router I've been able to stream just fine using my wifi.
Le Eco Super4 X55 owner here, 4k is my bitch.
Sony X800D here. Steaming 4k is great.
I'm able to stream 4K content through my Sony XBR-65X850D without an issue. I've used Netflix and Plex apps built in to the TV to stream it.
Probably helps that my TV is hardwired in to a Gigabit LAN and I have 150Mbps internet service.
My x810c plays 4k content from Netflix and Amazon no problem. I have not found a way to stream local 4k content without stuttering or quality loss. I use a Roku Ultra for everything besides casting. With every software update I hope the smart aspects of the TV will become more usable but they don't. The interface it's constantly lagging and I get restarts if I try to actually use Android TV. Great picture quality, though. 😉
My Sony TV cant handle local 4k transcoding, but the shield can. Also if youre watching local 4k media (the best in terms of quality, streaming is ugly) youll need ethernet too.
You NEED gigabit for any local NAS high bitrate content (lossless blueray) not just for 4k but for certain HD as well.
None (with the exception of the leeco) of the current smart tv's from pretty much anyone have gigabit network ports.
Q. For all Sony 4K Android TV owners....
When you play say 1080p HD Netflix and then play 4K Netflix after does the TV Auto resolution switch to its 2160p mode automatically ?
The reason I'm asking is 1080p > 2160p upscaling, for Netflix / Amazon etc is definitely better quality when done by a 4K TV than any external media player.
Yes, the TVs have hardware video decoder chips too.
My Sony XD93 does HDR/4K Amazon/Netflix just fine.