Played on keyboard or guitar?

I want to do a live cover of Snow Patrol & Martha Wainwright's 'Set Fire To The Third Bar' in a relatively small, relatively quiet coffee shop. My vocals are relatively low, a bit like Marina of Marina & The Diamonds, quite deep, but also a bit Diana Vickers, Florence Welch (Florence & The Machine), PJ Harvey, Patti Smiths. Should I play it on keyboard or acoustic guitar?