i've used both, albeit in very different guitars. the super distortion is a classic, but i much preferred the at-1. can't really sell you on one or the other but i found the at-1 to be a little more musical with a growlier midrange and a slightly softer, crunchier feel, for lack of a better term. The SD was crunchy for sure, but it was a little harsher sounding to my ears. But again, different guitars. SD was in a BC Rich Bich and the AT-1 was in a Kramer Baretta.