What song should i sing for the talent show?

I don"t know what to sing for the talent show!!!!!! I want to sing and play the guitar. PLZ can some one give me some suggestions. The songs Im the best at are "Halo" By: Beyonce, "Already Gone" By: Kelly Clarkson, "No One" By: Alisha keys, and "Falling Down" By: Selena Gomez