I'm pretty much in the same boat as you, OP: I got one last week and I already had all my PS4 Plus games, ACIV from a digital upgrade last year. I bought Wolfenstein last week and Injustice+Lego Marvel this week on sale.
Wolfenstein, Resogun and AC are getting most of the play time here. I feel Resogun is this gen's Geometry Wars and Wolfenstein is just awesome.
At this point, I'm not actively looking to buy more games. I don't have much interest in KZ and Knack in particular. And I'm not too sure about Infamous. I kind of solved the Infamous equation by preordering First Light. I figure that it will fill the tech demo role for cheaper than the main game and will allow me to see if I want to get the main game.
As for that second controller, we'll probably use it with Towerfall and Lego but the game I'm most looking forward to using it with is Minecraft. Coop was a life sucking experience on 360 for us.
I still have to check Transistor but TBH, at this point, I feel like we already have 3 months worth of gaming.
Edit: I'm also trying to refrain from buying anything until the August IGC games are announced.