i would recommend antec power supplies as a first choice (its a tad bit expensive)
Antec True Power Series TP-750
Antec True Power Quattro 850W
Antec Earthwatts 750 (for the enviromentally Friendly user)
There is thermaltake aswell and coolermaster psu too you can choose from.
Depends on what your budget is.
Take 2,I bought my TX750 from them and it's a brilliant psu