This is one of these topics where you will get 100's of responses in favor of just about every manufacturer. As far as the majors go I personally, I like Rancho's. I had Edlebrock IAS installed on my ford excursion diesel, and 3 of them were blown or leaking in less than a year and a half. I have never had a problem with Rancho's. I will tell you that if you get the 9000's, whatever setting you set them at, is where it will be forever, as the adjustment knobs freeze in position after a few months.