George Saint Pierre or Anderson Silva, best pound for pound fighter and why?

I would have to give the edge to George Saint Pierre but it's a tough one. Without question I believe George Saint Pierre has the most discipline and understanding of MMA, he always uses his head in a fight and has world renown trainers on his side that give him excellent advice unlike many other trainers during the fight. I can't wait to see GSP move up to welterweight somewhere in the near future (maybe a year?) and have a title fight against Silva. That is the best possible match up IN THE WORLD. At least in my opinion, but let's hear yours!