Not a lot in common between those three. The Sony has the potential to take the highest quality photos, but it the largest and most expensive; you cannot put it in a pocket. The Canon is an advanced compact with a slightly bigger sensor, a moderate zoom lens, and lots of control options. The Nikon is a primarily automatic camera for someone who mostly wants to point-and-shoot.
Okay, I am looking to purchase a new camera and I am in a debate with myself over the Sony nex-c3, Canon Powershot S100 and Nikon Coolpix S9100.