best old PC for media server

[Drake97]

Hello y'all,

I have the option to buy some sff type pc near me and the options are several Lenovo Thinkcentre, Dell Optiplex and HP Prodesk / Elitedesk. Which would be the best option according to the CPU age, cores, threads and ram for literally only me to watch videos in 4k hdr using jellyfin??, the PC's are:

Intel i3-7100 / 8GB ram DDR4
Intel i7-4770 / 8GB ram DDR3
Intel i5-6400 / 4GB ram DDR4
Intel i5-6500 / 8GB ram DDR4
Intel i5-3470 / 8GB ram DDR3

All these specifications would be to then increase the ram maybe and use it with a 2TB HDD and a SSD as primary and the use would be to only create a media server for own use at home.

as I mentioned, the only use for that media server will be to watch my own movies in 4k hdr (some with dolby atmos and/or dolby digital plus) and I'm a bit confused about 4k streaming and 4k transcoding.
I use as my primary device a Chromecast 4k with google TV, a samsung q600b soundbar and a 4k HDR compatible samsung TV (50RU7400).

Any recommendations would be appreciated as well as to know if I should go for something more "powerful" in that case.

Regards.