I've got my eye on the PS4, but like Groudon, there simply aren't any notable exclusive games I want for it that are currently available, or coming in the foresee-able future. If one has a half-decent PC complemented by a PS3 or 360, its existence feels a bit redundant at the moment.
The Wii U in my possession has seen quite a bit of use, though, between exclusive games like Super Mario 3D World, Pikmin 3, Wind Waker HD, New Super Luigi U, and the best multi-platform version of Need for Speed: Most Wanted. I'm still not sure if the tablet was a good investment for a mandatory accessory for the system, but the tablet is handy for off-screen play when someone else wants to use the TV (or if I want to watch a show while I play).