I bought the PS3 for GT5, and the XB360 for Forza (whatever number it was back then).
between the two consoles, I've had precisely four franchises: Forza, GT, GTA, Saints Row (I did buy Halo (whatever) a couple years ago).
i have exactly none of the games now. In fact, my PS3 is on ebay/CL, and the xbox is just sitting collecting dust.