Ok back to all seriousness now.
My choice has to be the Mini. Even if it does get thoroughly walloped by the Abarth 500 in terms of the cool factor, the JCW will run rings around the Abarth in terms of driveability and enjoyment.
I love the Abarth and I adore the image as much as I hate the New MINI II for being a gratuitous rehash of the New MINI I from a styling point of view. And I positively detest that MINI's interior. That said, once you've driven one and you've felt the kick, point and squirt ability of this car you be left in no doubt why the MINI is the still the dynamics class leader. (Renaultsport Clio III R27 almost as good but lacks torque to be as much outright fun.)