We have cars with Strange dbl adj and QA-1 singles. I like the Strange units better based on the difference between the clicks. Both have served us well this is the only way I have been able to come to a conclusion as to which is better.
To quantify, the Strange units are on a 2700lb Nova that runs 9.40s, 4-link and 14-31 tires. The QA-1s are on my personal roadster that runs 9.50s @2050, 4-link, 14-33's.
Since my car is not really that fast I could probably get away with just about any shock on it, that's why it is hard for my to decide which is a better shock. If I were to buy a set, these came with the car, I would probably buy Afco or Strange Dbls.
Curtis