Wow, that is a loaded question, since I have been listening to CCM since the 80's, and I think the first concert I went to was either Bryan Duncan or Amy Grant.  To answer in a conservative tone, I would have to say either Michael W. Smith b/c he was a very early influence to my ccm enjoyment, along side of Newsboys and my 80's fave, White Heart.  Comming full circle to 2008, I have been stuck on David Crowder Band since before "Can You Hear Us" even hit the store shelves.  Lincoln Brewester, and Jermey Camp play frequently on my Ipod these days, along with Jermey Riddle and the recently downloaded Article One.  OH, I forgot my other top fav, after DCB, is Switchfoot. Both DCB and Switchfoot I can listen to all day and never get tired of, not to metion I have all of their albums.  OK, its final, DCB and Switchfoot. 

P.S.  Looking for some more peeps, so head on over and say hello to me.