zvex super hard on, if you've got a tube amp its just about the best drive you can get. its also completely transparent with the OCD and fulldrive are not. I like the fulltone pedals (I've owned both) and the fulldrive is awesome in comp cut (put it in front of a blackface fender, crank up and hang on) but I find the super hard on to have a better base sound. and I like that on its own, the super hard on has absolutely no distortion going on, all it is is a gain boost. so when you're using it it really doesnt sound like a od pedal, its much more organic