[detaro]

Two come to mind immediately: https://www.tomshardware.com/ does. German magazine c't at least did, haven't looked at their reviews recently.

[Qub3d]

http://www.jonnyguru.com/ Has always done some pretty in-depth electrical profiling of PSUs. I usually check them when I need to buy one.

[formerly_proven]

Tweakpc, hardwareluxx, c't, computerbase and probably a few more all use pretty high end ATE (Chroma loads and such) for their PSU tests as well.

[zaarn]

c't still does very in depth testing like that when they do a larger PSU lineup test, though not for smaller individual tests.