Westa, I'm guessing you didn't have the new Sony Experience center in that BB.
I know all the 4K LG loops as well as the 4K LG display you saw. In my many trips to BB, I'd say the Sony 900B/950B and the Samsung 8500/9000 are superior displays relative to the LG. At least that's been my experience. They haven't fared well in several reviews either.
As for 4K material, the user selectable material within the Sony Experience centers, are the best I've seen and allow YOU to choose the material you want. You can play 4K, up scaled HD or even live TV. Sony shows some confidence in their displays to allow this flexibility. I think this run circles around the LG loop or even the Samsung demo.
But this brings up an important point regarding comparing these 4K displays, how do you do it? Each manufacturer has different, proprietary material on each of their displays. The Sony demos are very different than the Samsung and those are very different than the LG. Each was shot differently with very different scenes, making it extremely difficult to compare.
For me it's easier, since I have my own 4K material on a thumb drive that I can simply insert into any 2nd gen, 4K display I want. Same material on every display. For someone with no 4K camera, I'd suggest downloading some known 4K quality content on to a thumb drive and doing the same thing. There's nothing better than seeing the same material on different displays.