Not a popular answer, but Apple TV is the best out of the box experience. Zero ads, massive longevity. Mine is like 7 years old and still running the latest tvOS.
If you have the cash and inclination, Nvidia Shield is the hackers choice. Zero hardware upgrades in years tho, but software aplenty.
Just don’t let your smart TV access the internet in any situation, there’s no need. It’s just a stupid display.