Wow, good stuff. Um, well, it's pretty hard to narrow it down to one band. I think most people will say the Beatles. I wanna say REM, but it's difficult to be influenced by a band if you can't understand half their lyrics. I almost wanted to say Petra, the Christian rock band. Living Colour carried me for a few years. In the last few years, Rufus Wainwright and Amy Winehouse have been very inspiring for me.
Still, in the end, if I could see anyone perform, living or dead, I would say Luke Kelly, the Irish folk singer from the 60's/70's. His voice cuts right to the soul. The feeling in his music can move me to tears. Especially when he sings about The Town I loved So Well or Scorn Not His Simplicity. Absolutely love his music and wish I could have seen him live.