I've been randomly messing around with Topaz Video AI for a couple years now. It's a neat tool but I have trouble ignoring the typical "tells" of AI upscaled footage (thinking primarily of a waxy look). That's probably on me for not tweaking the settings enough, although I've noticed the same...
This is my personal preference in order of what I think is the highest quality:
Blu-ray (Abandoned now but several studios released extremely high quality discs back around 2009-2012-ish)
Digital for HD content (Since DVD is the only physical option these days)
DVD for SD content (Anything old...
Looking for scenes where pornstars keep their heels on for at least some of the fucking.
For example, Abella Anderson keeps her heels on for the entirety of her scene in Jules Jordan's "Hot Anal Injection 2"
https://www.julesjordan.com/trial/scenes/abella-anderson-anal_vids.html