Jonnyguru does excellent PSU reviews, but as far as detail goes, HardwareSecrets is like Jonnyguru on steroids. HardOCP and Xbitlabs test PSUs properly as well (load testing, waveform analysis, etc). I do believe, however, that PSU reviews are extremely straightforward and objective, without a lot of variables to measure. The same cannot be said of motherboards, GPUs, or even CPUs.
Tom's does excellent overviews, but usually only provides some of the "data points" that are of interest. To be fair, the same can be said of most review sites; it depends on what "data points" are of greatest interest to you. Anandtech and Guru3D are other good sources of reviews.