I've had most of the interfaces mentioned. FireTV, Roku, Samsung, LG, and a couple of others.
What I've found is that just like any other computer, there are differences in price and capabilities. The worst interface I've had is a Samsung TV in my bedroom. It was a cheapish TV, and it showed. The interface was super clunky, and slow. I replaced it with a firestick, and then when that one acted up another firestick like 5 years later. The firestick worked great, and had all the apps I needed and more.
My mom has a big and expensive Samsung and the TV interface works fine and has lots of apps. My cheap Roku TV in my barn works really good, as does my LG in my living room.
Never used Chromecast or whatever Google called their firestick.