For me there is no question. All you have to ask is which came first Blues or Shred? I hope you all answered blues so the next question is what style did most shredders learn before they learnt to shred? I think the answer in most cases would be blues again.
Personally I hate shredding and can't see the point of it. I can listen to about 30 seconds of Satriani before i want to put my boot through the CD player. Wickipedia defines shredding as " a guitar playing style where technical proficiency is the major goal".I.E. technique above phrasing, melody, emotion or any of the other thing for which the Electric guitar is justifiably famous.
Can anybody put forward a convincing argument to me that ANY Satriani song is more beautiful the The Thrill Is Gone?