"Hello, I Love You"
Again, easy one. I've never minded Cory's voice but he was obviously not as trained as some of the other actors on the show, so when I heard this song I was honestly impressed and ever since then I think he's just kept improving :)
Plus, um, Kurt's face in this song. Boy was not thinking innocent things, that's for sure xP (This was also one of the first times I found Kurt attractive, I think, so double bonus!!)