I know I'm completely alone in this opinion, but I think Unstoppable would be a good single. She nails that late 70s / early 80s disco funk sound so effortlessly on this track. She doesn't always sound... at ease with funk or r&b influences, but from the slinky verses to her gorgeous soprano coos in the chorus, she sounds utterly at home here. And Troy Miller's production is immaculate. The song's influences are clearly on its sleeve but it doesn't feel like total pastiche either. And it's also uplifting without being syrupy.
I really love this album, but I feel like most of the other potential future singles mentioned on this thread are either so camp that they're unlikely to appeal to anyone who doesn't already own the album and/or they're going to sound a touch shrill given Sky's special turn-everything-up-to-11 touch.