PS4 and XBone: Nothing I can think of. It isn't worth paying an online fee for games that I would not get anything more than a mediocre experience from, especially when having to deal with the online community. I've been there and done that and for me it is time for something different. I bought a XBox 360 and Gold a few years back and learned that it just isn't worth the price to me.
Now if we just throw the reality of this gen right out the window:
A new Lunar AND a new Suikoden that are completely fleshed out with massive budgets. Both games could be cell shaded and I would be completely fine with it due to that being the art direction of these games anyways (to reduce development costs). I can't just say jrpgs because in reality I don't just want any jrpg on the market, there are specific ones. Due to the team for Suikoden have disbanded and left Konami (and the games not really selling that well with even the best selling game Suikoden 3 selling less than a million copies), and the studio that made Lunar is no longer around, these will not happen.
Also, if Nintendo gets really desperate for money and makes a deal with Square Enix and Monolith Soft to completely redo or make a huge budgeted sequel for Xenogears from the ground up for one of the other systems (for a percentage of profits of course) I'd get one. Again though, in reality this isn't going to happen.
COULD there be something that really grabs my attention and makes me buy a PS4 or Xbone? Sure, I just haven't seen it nor can I really think of it.