I just switched from the semi-modular Antec Truepower New Blue 750 (had to rma) to the fully modular Seasonic X-650.

I highly recommend that whatever psu you get, make sure it's fully modular. I have seen no semi-modular psu where the manufacturer permanently connects only the ATX-24 and the 4+4 mb 12v power connector. They all throw in something you end up tucking away. I love having only the cables I want.