Actually, you might not want to pick up Knack given that's it's pretty likely to be a PS+ in the next year.
You missed Resogun PS+, so you might want to pick that up - it's an amazing game.
InFamous: Second Son and InFamous: First Light are both very good (depending on your tastes).
Killzone: Shadowfall is pretty average but if you can find it for cheap, I would get it.
Destiny is OK for about 15 hours, and shit for the other 100+ you'll end up playing trying to find 'the good part' of the game.
Diablo 3: Reaper of Souls - the PS4 edition is argubly the best version of the game, especially if you have someone to play couch co-op with.
Lara Croft and the Temple of Osiris feels built for a controller, also better with couch co-op.
Transistor is on PS+ right now. Get it.
The Order: 1886 in a week.