I dont mind people saying who they think are good because i can think fair enough maybe thats what they like and i'm sure a lot of those people would be angry to hear me talking about how bad i think that guitarist is, but sorry for insulting you like that seve420 didnt mean it in a nasty way ;)
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.