well, I think Down, Coma and No Way Out show the most vocal range, and they're probably the hardest songs to sing. His range is incredible on all those songs.
I think the whole Purple album his voice sounded the best of his life, but I also thought he sounded very strong on Slither. If you go back to Slither and compare that voice to what you hear on Happy in Galoshes, there's a major difference to me.
I thought his vocals on Tiny Music were weak. Part of that was the style, but I also think it was much inferior to his vocals on Purple. #4 and SLDD were better vocal efforts, but the lyrics for me weren't as good. I actually thought both VR records were very strong from a vocal standpoint.
But if you pinned me down and asked me what my favorite track is as far as Scott's voice sounding best, I'd probably pick Silvergun Superman.