Is Semi-Modular PSU, also the Recommended PSU Wattage (W) for the R9 290 is 650w. The XFX is one of the best (price/performance) power supply which is made by Seasonic.
The Super Flower recommended above is the best of the bunch both in efficiency as well as in voltage regulation and ripple and noise. The Seasonic M12 II and XFX are basically the same unit since Seasonic makes all XFX power supplies and they would be still excellent but a small step down from the Super Flower. The Corsair units are also very good but they would be third on the list.