UHD/BD/DVD Disc Player

[MAUL xx]

I plan to get a 4k TV this November but I already own several UHD disks like Blade Runner Final Cut & 2049, Close Encounters, Logan, Dunkirk, E.T & now Predator. I'm thinking it may be worth getting a 4k player now before actually getting the TV.
I did some looking & since Oppo is all but off the table for me now it looks like the Sony x700 or the Panasonic ub900 are my best options. I did see someone recommending a Panasonic ub820 so that may be another option.
What are your thoughts & recommendations?
What's the difference between the Panasonic ub900 & the ub820? This is the first I've heard of a 820.