If you want a great variety of games, you really can't go wrong with either a PS4 or XBOX One, it all comes down to which developers you're a bigger fan of. That holds true if you're just looking for Japanese games, as I think even Microsoft will get their fair share when it's all said and done.

As far as the longevity question in the OP, I think Nintendo is going to give the Wii U its obligatory 4 years and release the next one. It's tracking behind the Dreamcast iirc and we've just about crossed off all the ideas on the "What Will Save the Wii U?" chalkboard.