Seasonic PSUs are very good PSUs. Our engineer hooked up the scope to measure the voltage between the Seasonic and the Seventeam PSUs, and the Seasonic PSUs delivered (more) stable voltage than the Seventeam. We're running proprietary hardware and switching PSUs made a huge difference.
I have one you ought to add; the Chiefmax line are just overrated crap IMHO. The tests I've read say they cannot deliver anything close to what they advertise and the failure rate is phenomenal. They at least have never taken out any hardware with them that I have seen and I guess that is why my old boss likes them; cheap easy fix and at least the customers "safe", but it seems ethically questionable to me.
The Bestec 300W that so many OEMs used and that they still sell some places, might as well have been engineered to kill motherboards, I have seen so many dead ones, but from what I read the other models are not so bad and it is just some bad caps inside, but otherwise not a bad unit, but I don't think they sell any except the OEMs replacing ones for too much money with OEM stuff. I guess it's like a lot of things, just because a bad batch was mass produced doesn't necessarily indicate bad workmanship from the company, but I always replace those no matter what the model just out of paranoia.
I recently got a Coolermaster PSU (can't remember the model) and connected it to an Asus P5G41T. The CPU fan would turn on for a couple of seconds, then off again (PSUvoltage set correclty). I then connected and old Powerman (Inwin) PSU, using a 20-pin to 24-pin power connector and the system booted. I had the bare minimum connected to the motherboard for troubleshooting.
I took it back to the store and they tested it and told me the PSU was good. I got an exchange for an Enermax PSU, which worked fine.
Yes, The CM PSU would not boot the system. The Powerman PSU I tried right after had no issues booting. The exchange I got from the store was an Enermax, which booted as well. The store tested the CM PSU as "good." That puzzled me.