I just bought a new Samsung QLED 65 inch 4k tv. Its to replace a projection (yes that is right!) HD tv from SONY from approx 2002 in the kids room in the basement. So far I haven't been able to play with it much. Kids are using it for XBOX one S. I did watch some 4k scenic videos on YouTube which looked awesome. My 8 year old plasma tv still seems to do motion better than this new TV however.
Get your kids a computer monitor to play xbox on they'll thank you for it in the long run. You'll also get your TV back.