I think ANTR a notable inclusion to this discussion. It is surely one of their heaviest songs, even the middle section is heavy, the verses in Beautiful Agony, especially the 2nd one, seems to get overlooked by the main theme/chorus of that section. Understandably so, as that is arguably the highlight of the entire piece. Even the initial transition into the BA section is heavy, despite the distorted guitars going clean. You don't need distortion on an electric guitar to be heavy.