After reading tons of reviews, I've always gone with Samsung. We are very happy with the ones we have. Our main TV is a 65" Samsung Smart TV.
I'm not real savvy on Roku either so I searched this up for ya.
https://blog.roku.com/smart-tv-vs-roku-tvEdit: I agree with the above. Costco and Sam's are pretty cheap on a lot of stuff. TV's are not one of them.