What's the best 4K TV I can buy for around £1000?

Hey all, I've looking at upgrading my current tv and I definitely want to go 4K, I know that there's a lot of great 1080p screens out there but I definitely want to futureproof my TV. I plan on streaming Netflix/Amazon Prime 4K content, as well as playing PS4 games, and content from a USB stick.

I've been researching into it and apparently I need to make sure it has HDMI 2.0, is there anything else the TV will need to have for the future? I'm worried that in 2 years time I wont be able to do X because my TV doesn't have Y and I should have made sure it had that when I bought the thing but i didn't because I'm an idiot etc.

My budget is around £1000 and under (I'm from england), I'm looking at screens 50+ inches, not mega fussed about 3D, but I do plan on playing alot of PS4 games on it. I like the look of the Panasonic TX-50CX700 and the Samsung UE55JU6400 but I don't want to buy anything without getting the advice of experts.

If you can give me any advice, tips or suggestions I'd really appreciate it, thanks!

Edit: HDMI 2.0 not USB 2.0