Like Lifewish alludes to, it's going to depend on your gaming preferences.
My first games were Lego Marvel Heroes and Black Flag, with Shadow Fall, Knack and NFS Rivals not too long thereafter.
Lego Marvel Heroes is a BLAST if you have kids/nephews/are a big kid. Some good length too if you are a completionist.
Assassin's Creed IV: Black Flag, well it's the same as the PS3/360 version with better graphics. If you liked the series you have already likely played it.
Killzone: Shadow Fall... I was okay with the first three games, not a huge fan of them, just okay with them. I've yet to beat this. In fact, after my initial couple hours of playing it, I don't believe it's been in my PS4 since.
Knack, for as mixed of reviews as it got I really enjoyed it. It's quite a bit of a throwback to the original Crash games, somewhat kiddy looking while also being rather difficult and punishing.
Need for Speed: Rivals, I was extremely disappointed in. I loved the first two games, but this one kinda went off the rails a bit and added elements that just made it annoying to play.