I absolutely love both my Wii U and 3Ds.
The Wii U is an absolutely phenomenal machine. It does what it needs to do and no less, no more. It plays games. And great ones at that. That is provided you don't have the illusory bias that Nintendo merely rehashes games. They simply don't. That said, the Gamepad is pretty damn cool. Not only does it provide an ample mechanism to introduce new gameplay mechanics, it also lets you play games on it as opposed to the big screen. Right out of the box, without having to shell out another $200. Admittedly, not all developers utilize the Gamepad properly or to its fullest extent. The first party lineup, as always, is amazing so far. Nintendo just simply knows how to create a good game. And I can't wait for the system to really pick up in momentum so we can see more third party support for it.
The Virtual Console is just fantastic as well. You can find a plethora of older games that span across all the generations. And they will be adding GCN titles soon, I assure you. All of these have full features that an emulator on PC would have. State saves, quick loads, and the goodies. You can play them on the TV or the Gamepad as well. And they also have full functionality with the Wii U Pro Controller.
The 3DS, in my opinion, is superior to the Vita. Not in power, but in software. There are just simply a hell of a lot more good games to play on the 3DS than there are the Vita at this time. And, again, the first party and exclusive titles are amazing. I can only hope Sony supports the Vita to such an extent. The lack of another analog actually does nothing to hamper gameplay. All the games I have ever encountered control extremely well.
In the end, it is all about the fun. And Nintendo is all about the fun.