Actually that post just listed my three favourite death metal vocalists, so we're almost in complete agreement
I don't find the enunciation of Mikael and Peter to be much better than George's to be honest- there's a similar level of hit and miss so far as I can tell. Moreover, enunciation is fairly important to me but not hugely important- bands like Credence Clearwater revival are a great example of awesome music where I have no fucking idea what the singer is saying.
What makes George an awesome vocalist is his sense of rhythm- both vocal and instrumental- and how the two interact. His emphasis of words and phrases shows a really strong understanding of the music beneath it that the majority of brutal death vocalists really lack. After all, the growl is nothing but an emotive rhythmic device. It's clearly not melodic, so what it adds to the music is a polyrhythm over the instruments and a human/emotive method of distinguishing parts of the song from one another.
I think George is one of the best in the business at recognising this and using his voice to add a layer of complexity and brutality to the music. As for his tone, it is raw power but it is also carefully controlled. Comparing him to Chris Barnes in particular is pretty crude I think, Barnes has an incredibly weak and undisciplined growl- the complete opposite of Fisher.
