I love both the PS4 and my NS so I'll give you my take:
First off, PS4 games look beautiful. They're boasting an exclusive library of high caliber complex story driven masterpieces.
If you're looking for interactive cinematic experiences they do it better than all. Most non-exclusives make it here as well so you'll get all your Destiny, Call of Duty type games as well. It plays blurays, has Spotify, and boasts a respectable online presence.
Nintendo Switch... Play it on your tv, pull it out of the dock and on the go. Many evenings I find myself laying in bed for a bit winding down after a long day getting a quick game in. Nintendo kills with its charm and quirkiness.
Zelda BOTW, Mario Kart 8 Deluxe, Splatoon 2, and now Mario Odyssey present 4 heavy hitters within a 7 month period also sprinkled along with several other nice exclusives (Fire Emblem Warriors, Pokken Tournament, ARMs) and lots of indie support. Also they're attracting third party's! Skyrim, LA Noire, Doom, and Wolfenstein 2 will be dropping on their console too, soon.
Either way you're in a winning situation just look at each ones strengths.