PS4 + Vita remote play needs work. Sitting on my couch and playing Lego Marvel led to constant sluggish slowdown and connection breaking. I'm like three feet away from my PS4 and router! Compared to Wii U off-tv play, it's a massive downgrade. I suppose Vita play is tethered to the wifi range and not the Wii U console range, but my experience has proven rough. Enough that I really won't bother with it again until its proven more effective.
The Vita is a decent kit with a decent selection of games, especially if you factor PSP games off PSN that add to the library. Still, it's selection is lacking. P4 Golden is fantastic and will last a good while, and there are a few other gems, but it's all very niche and many titles might not gel with personal tastes. I was surprised by Tearaway, Muramasa, and a few others, but not everyone would agree. Most of my time has been spent on older Backwards compatible classics from the PS1 and PSP era.
I am not a fan of the sticks really and find games like Uncharted and Killzone which rely heavily on their use, very frustrating. Aiming sensitivity, deadzones, etc... never quite feel right and despite spending time with menu adjustments, I can never reach a comfortable sweet zone. I all but have given up on both of these titles in the first couple hours.
3DS has proven to have a lot of vitality this year. I can't recommend a 3DS more first.