A mushy brake pedal would surely mean air in the system? or is the pedal just soft and light to press - as it should be, but rarely is?
I've only ever fitted standard spec pads and rotors (mostly aftermarket brands) and they have worked nicely right out of the box. The only thing I do is to clean the oil off the rotors before fitting them; White spirit, rubbed over with a cloth, then a rinse with de-greaser solution and a dry over with a clean rag. I know you're not supposed to, but it works and I haven't had a problem with it in 20 years.