In the ATX world, Seasonic, Flextronic, Superflower and Delta are king. They make the majority of high quality PSUs sold by Corsair, EVGA, Antec, etc.
Flextronic and Superflower are strictly OEM as I recall. Hard to tell sometimes what power supplies are made by them.
Delta I'd forgotten about - but I still have that one model made specifically for some of the Tyan dual-Athlon motherboards.
I just wish it had more +12V instead of a ton of +3.3V and poor efficiency (it LONG predates 80Plus).
Newegg RMA is good if the item dies quickly (infant mortality is the most common timeframe of failure for ANYTHING electronic, thank goodness).
They also are a lot easier to search for applicable PS - Amazon sometimes has better pricing but their search functionality is almost non-existant.
Flextronic might very well be, but Superflower sells PSUs under their own brand mainly in Europe. All of those fantastic EVGA PSUs are also sold under the Superflower banner in Europe alongside EVGA.
Yeah, probably best to not use such an old PSU with miners. They come from a time when 3.3v and 5v in PSUs were the main rails and generally have ~70% efficiency.