I am a TrueNAS user, but not a Plex-user.
My TrueNAS box uses around 130W idle, going down to ~105W when idling for >10-15 minutes, and up to 210W under load (Xeon E1245 with 10x 18TB HDD raidz2 plus 1 HDD, 1x 10GBit SFP+)
My thought would be the "X13SAZ-F with i5-13500", because it's a newer...