I voted Petrucci. It's close between him and Moore for me. I originally voted Moore and took it back. Mostly it is Petrucci's awake lyrics that get me. A mind beside itself, Scarred, Innocence Faded, they are all great. He also just has a lot more to go off of. After SDOIT, I don't find as much in his lyrics but, before that, his stuff is incredible. Metroplis, Another Day, Under a Glass Moon. I know this is an unpopular opinion but I also love Take away my Pain. So it's got to be Petrucci.
Like I said, it is difficult with Kevin Moore. Space Dye Vest might have some of my favorite lyrics of any DT song, but, overall, I think I've got to go with Petrucci.