I have an 18 watt marshall clone, so it gets the best distortion you can get up to a point, but if I want to x-treme distortion what is the best peddle?
the moment I saw someone vote for AC/DC for the "heaviest" guitar sound - I realized that not only is music very very subjective, but some people are just stupid on top of that.
so explain the kind of sound you like/want/must have and we'll tell you 39 different ways to acheive things that sound good to us...regardless of what you say.
with all of that being said.
I like my Mesa V-Twin, and my Danelectro Daddy-O
They're not the heaviest. But they work for the sounds I like and need.