My "favourite" guitarist used to be Michael Angelo but now i just like loads of different guitarists and like a lot of different bands.
I also really like Jason Beckers stuff. He is a great guitarist considering how young he was when he was playing great stuff on guitar.
I think for metal dime was one of my first influences. I think he had some really cool riffs when he was with "pantera". There are also a few other good metal players like the guitarist from "grave digger" has some cool riffs and a great tone :)
By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.