SEGA customer service thinks Bayonetta 1 and 2 are the same game, just with multiplayer and cosmetic changes
The second Bayonetta as you well know is being published by Nintendo exclusively for the Wii U. Both games have been developed by Platinum games. That said, the decision on which version to purchase is really up to you. The games are exactly the same except the WiiU version has a two player mode and the Bayonetta character has different hair and her costume is different.
If those additional features are not important to you, then by all means don't hesitate to pick up the PS3 or Xbox version. Good Luck and we hope you enjoy whatever version you decide on.
Someone at SEGA customer service is about to have a very, very bad Monday.