Seasonic has the lowest ripple of all PSUs across their entire line of products. Even their low end PSUs have much better ripple suppression than most mid to high end models from other brands.On top of this, I've never seen a seasonic PSU fail before either.
You can pick up any Seasonic unit and you'll have a reliable, well regulated, efficient, quiet PSU. Don't know many other mfrs that can say that, about any product.
I love my X series units more than anything, but I really want one of the new Platinums... Here's hoping they refresh the whole line, as a Platinum 400 (I'd say Fanless, but with the new Hybrid Fan on-off, who needs fanless??) would just be awesome. My X Golds are going to be awesome for years to come, and so far after two years, few platforms have come close to the X series's overall excellence. You can get a PSU based on Seasonic's platforms, but I say just head straight to the source.
On top of solid build quality and performance I like Seasonic for their high efficiency and low noise. Their definitely one of the quietest power supplies you can buy.
Incredible quality. I recommend Seasonic to pretty much anyone looking to get a PSU -- for low end, high end and in between. I'm running an x650 in my current desktop and loving it.