Seasonic has a reputation for high quality power supplies. Seasonic is an actual manufacturer and makes some of the high quality Corsair and PC Power & Cooling psu's. Corsair and PCP&C do not make their own psu's.
Here are some links to actual technical reviews and test results for the Seasonic S12 series of psu's:
baskinghobo - If you are positive you need a 500 watt power supply for your system, then why are you asking about 430 watt power supply?
helloworld_98 - we have no idea what baskinghobo needs simply because the pc components, configuration, and games played were not listed. It is difficult to render an opinion when the information is missing.