Yeah, the G-Series is "only" very good. Seasonic X-Series/Platinum (and their new Titanium units, I'd guess) are excellent. Platinum is usually worth it, since the price difference is typically small, relative to the X-Series.
Superflower also has some very nice designs, but they seem to rely on capacitors on the cables for ripple control and they always seem to be paired with "meh" fans.