QUOTE(chocobo7779 @ Mar 28 2014, 07:56 PM)
FYI, the VP550P is a Delta-manufactured unit, which is considered one of the best OEMs for PSUs... Prebuilt machines tend to pick Delta as OEM for their power supplies... The Antec Signature series are a good testimony to that.

Note that the VP550P does not have Active PFC, and hence the unit only accepts 240V, and it does not have 80+ certification due to lack of an Active PFC circuit.

Thanks, chocobo7779, for sharing the OEM on the Antec. It is also stated in the techpowerup review as well that Delta makes the Antec PSU. Delta is one of the largest manufacturers of power supplies, and they do have large contracts with the OEMs like Dells, HPs, Lenovos, etc. This does provide the opportunity for Delta to gain a lot of experience in the design and manufacture of PSUs.
I consider a few things when assessing between ATX PSUs, and trying to decide which to buy, with the fundamental facts that the PSUs being compared are in stock at my favorite seller, similar in cost, and similar in power output.
First priority is the PSU design including choice of components, and this can only be obtained through reviews that open up the PSUs, and dissect their designs. Second priority are the load measurements of the PSU which is validation of the design, especially the efficiency measurements, power quality, and of course the noise level. Third priority is the quality of the assembly including assessment of the PCB soldering quality, and components used like capacitors and MOSFETs, and this provides an idea of how reliable the PSU can be. Fourth priority is the manufacturer, and I would only be wary if the manufacturer was either totally unknown, or is infamous for bad design and/or manufacturing quality.
The original Signature series that made Antec famous was a very good design. However, the Basiq is not the same design as the Signature, and therefore the performance will be different. Unlike what you have mentioned, the Basiq's design does include active PFC, but the design is only using one MOSFET so it handles 230V only, and I am not sure what is the reason it is done that way, maybe to save cost. The Basiq's load measurements in techpowerup show average to below average performance.