1) Playstation 3
2) Wii
3) Xbox 360
PS3 has a lot of exclusives. Since you like superhero games, try out inFamous. Move is more accurate and can support gameplay on games like Killzone, SOCOM, Resistance, and, for the little kids, LittleBigPlanet. Free online.
Wii also has a lot of exclusives. Not many of them have online mutliplayer though. The motion control system is very nice. Not AS accurate as Move, but still really great. Free online, though.
Xbox has very few exclusives. None are superhero games. Kinect can't do a whole lot in games not specifically made for the peripheral. Only games like Kinectimals and other Kinect games use it deeply. The Kinect doesn't use controllers, so it's not very accurate or easy to control. $60 a year for online.