Best Prog Singer?

The vocals on Sleepwalkers are really the typical gritty singing that most good heavy metal singers are capable of doing.  From there to full on grunting is a long way; grunting is actually a very specialised skill irrespective of how much people may or may not like it in music.  Sleepwalkers is not far off Rob Halford but that's it.  And Ian Gillian was already doing gritty singing with Deep Purple for a long time by then.  It's just a guess but Halford is more likely to have derived his clean wailing from Hammill and the gritty singing from Gillian.  I sometimes wonder if Ozzy Osbourne fanboism in the media has obscured Gillian's importance to the development of metal vocals because all the three great metal singers of the 70s and 80s - Halford, Dio and Bruce Dickinson - cite him as a major influence.  As for punk, Hammill's singing was way beyond the grasp of typical punk, sorry to say that, so I doubt it.  I guess they respected the grit and darkness of VDGG's music which was also captured in Hammill's vocals.  Only Devoto (Magazine) ever evoked Hammill for me and he still sings in a kind of intentionally offkey way.  Give him a ballad and he will still sing like that.  I don't doubt that Hammill was a major influence on Halford and Dickinson but I wonder if he influenced even James Hetfield, let alone somebody like Chris Barnes.

Different strokes then.  I love the saxophone more than any other instrument for atonal/free improv music.  Which is kind of why it was so popular in jazz at the time.  I have no problem with both Hammill and Jackson having a lot of space in a track that's overall tending to soft/melodic.  In prog, when the music gets chaotic I don't like too much of vocals.  It gets distracting for me. I want to focus on the music in such cases.  I don't deny that taken in isolation, Hammill may have sounded brilliant with the more aggressive/darker aspects of VDGG's music.  But the overall package doesn't work for me.  

It is quite possible that Hammill was a major influence on harsh vocals in metal but not the absolute extreme end of the spectrum.  I am thinking more Halford/Bruce Dickinson.  Both cited Hammill as an influence.  Halford's timbre too is not far off Hammill's though his high register is much more like Gillian plus a lot of his own original insight.  But in their softer tracks like Here come the tears/Dreamer Deceiver the Hammill like quality comes through.  Halford is not especially beloved on this forum so I am going to get called heresy on this but I stand by the comparison.  On the other hand, the grunting/shrieking aspect of metal vocals was influenced more by punk's own multiple mutations starting with hardcore punk which further evolved into grindcore.  Grindcore was death metal before death metal reached maturation.  Some of the more punkish bands of the NWOBHM like, especially, Venom, may have also influenced the development of harsh vocals in metal.

Meant to respond to this earlier but couldn't find the time and it slipped my mind.  The pitch is one of the main reasons why he's so unique.  He's a man with a mezzo's pitch!  It's evident even when he speaks that he's not faking it, his voice IS that high.  My guess is that Benoit David/Jon Davison may have been trying to project that pitch artificially because Yes has such a huge market.  In David's case it certainly seemed to end up in problems.  Also he has a pretty supple voice and what I have seen is male rock singers struggle to sing like that, you know with so much melody.  The women can do it and I have found Corinne Drewery (Swing Out Sister) to vaguely evoke Jon Anderson and I doubt she was influenced by him in the slightest.

Anyhow, the most convincing Jon Anderson impression I have heard was not any of the other Yes singers but Steve Hillage on Khan. Especially the song Stranded.