Good acoustic songs to sing.?

For my junior year I'm going to be competing in this thing called Junior miss. And my Talent is going to be playing guitar and singing but I need help picking out some songs that I like. I've been playing guitar for three years but I would much prefer something that is either barre chords or just regular chords and not much picking because i'm going to be singing. I can sing fairly well, but im not the best....Any suggestions?