I can't really speak for the 3DS because I never owned one.
I'll make a small case for the PSP though. It has some great titles and a lot of solid ones underneath that too. I had no interest in most of its biggest releases - the GTAs, the Metal Gears, the God of Wars, the Final Fantasies, no interest whatsoever - and yet there were still plenty of games that did interest me, which speaks to the depth of its library. Plus there was a lot of breadth in terms of genres. Its library, like the platform in general, is seriously overlooked - perhaps because of what followed it.
And I know the Vita has its dedicated fans, but well... I bought one at launch and I don't think I played it for more than a few months, despite being able to appreciate that it's a great bit of kit; in short, I gave up on it sooner than Sony did, and that's saying something. That has somewhat tainted the PSP's legacy I think, although even before the Vita came along the PSP was under-estimated (the frigging thing sold over 80 million - 80 million! That's almost on the same level as the Xbox 360 and PS3, which always blows my mind).