Note: You can get a refurbished 39/50-inch versions from Amazon Warehouse for $353/$549.
While these are HDTVs, many will use them as computer displays which yield 3840×2160 resolutions. They run 4K at 30Hz via HDMI 1.4 or 1080P at 120Hz and get 4/5 star reviews. They have 3 HDMI inputs, Tuner input and 2 USB inputs and support 4K upscaling. Check out our review using it as a display for a 2013 MacBook Pro.