I finally got around to posting some encodes comparing x264 --hevc-aq with --aq-mode 4. I reran my old tests using the latest x265 and new parameters. These are 1 Mbps. Just 2-pass VBR at veryslow; the UltraPlacebo versions to follow.
HEVC-AQ
AQ-MODE 4
Curious on which the rest of you think is superior.