Brand is not equal to quality for sure, but i use "some products " from both Seasonic and Corsair. And they works fine for me. That is the reason way i recommend them......
Corsair CX450 and System Power 9 400w have both provide 80 PLUS Bronze efficiency. Corsair CX450 at this point is little bit cheaper. But System Power 9 have 3 years manufacturer’s warranty.