My faverate would have to be "Amazing Grace". For some reason I play the heck out of that song in practice. Its a very soothing song.
I play a decent version of "El Shaddai" that uses basic chords except for a few that I get to move around the fretboard for - woo hoo!
I learned a version of "Amazing Grace" done to the tune of "House of the Rising Sun" from a very Godly man named Terry Bennett who has since gone to be with the Lord. I last played that at my father's funeral in May :(
Also, I love "O Holy Night" at Christmas, and of course "Silent Night" - 1st verse sung in German - then repeated in English :)
I have composed 2 songs with God's help - "My Savior Lives" and "You Need to Believe" - maybe I'll find some way to get them up here someday...
Oh, and these are all played fingerstyle...
I have to agree "Amazing Grace", because it fits my life in so many ways, and because of the truth of the message of the song. Lately, though, I have been playing it as an instrumental; fingerstyle in DADGAD, a modification of William Coulter's arrangement. I haven't recorded it yet. Maybe I can do that soon and share here.