Check out TCL. They caught my eye a couple of years ago because their prices were fantastic, but I figured I'd wait and see for a while. When I was outfitting our new office at the airport, I asked our CEO about them because there's about a dozen of them scattered around the offices of his investment company, and he gave them the thumbs up, so I just bought a 65-incher in October. (BTW, I was *really* impressed with the mount I got for that one from Mounting Dream too - Fantastic product).
So, after doing a bit more research, I got a TCL 55R613 at Costco. $399, 4K/HDR, local dimming, and a built-in Roku. I bought an AppleTV to go with it as we have bought a fair amount of content from there, but it turns out Apple has an AppleTV app available on Roku now, so I returned the AppleTV.
Really impressed so far. Even the design of the box is well thought out, and the setup for the TV and Roku is all done at once, in a smooth, quick process. Definitely worth a look when you're in the market . . .