I have run Zimmermans on all of my cars.
No question, they are good - the zinc coating keeps the hats rust free plus the vents on the front rotors.
I just put a new set on my A4 paired with Brembo pads (reds).
I've never used Powerstop before...now I must investigate as my rotors are nearing replacement...great tip, and the pricing appeals to my thrifty nature!