I've owned an EHX Q-Tron+ (XO), Maxon AF-9, and a Robot Factory Meatwad. My favorite has probably been the Q-Tron, because it gave me the wettest/quackiest/funkiest sound. I think the Meatwad was far more versatile, thick, and tweakable though. I really disliked the Maxon, it was just way too...