We have a Roku attached to an LG TV. We also have a small Roku TV in another room. I like the Roku interface the best. For now, it is the industry leader, so you know all the apps will be made to run on Roku.
We use the built-in LG smart TV apps when possible because we get a noticeably better 4K and upscaled picture. Their app selection is good, but not as robust as Roku, like no BYU TV.