DS......I havent touched my PSP in more than a year, though it does have good games. DS is probably best for you now cause it has BC with GBA games. PSP may be good for you if you want a all in one multimedia device, but if you want games Id go for DS.
Getting an XBOX One for me is like being in a bad relationship but staying together because we have kids. XBone we have 20000+ achievement points, 2+ years of XBL Gold and 20000+ MS points. I think its best we stay together if only for the MS points.
Nintendo Treehouse is what happens when a publisher is confident and proud of its games and doesn't need to show CGI lies for five minutes.