Thank you so much for your reply, you saved me a lot , here!
I just wish 4k disc gets more cheaper and a better packaging on the discs , because i experienced some titles like the Toy Story 4 , the 4k disc was stacked on top of other disc and somehow had a skip on the movie while playing and same as the Movie Black Hawk Down 4k version - stacked and somehow scratched the disc and on around 7 mins in the movie ,it stalls , everytime. so the manufacture need a better work , on the disc cover and have a divider tray for each disc. I am trying to get every new movies that i wanted , on 4k format for my collection, but if price is very different , older movies so cheap on blue ray , is hard to skip , then go for the 4k