I'm with you.
I bought the Xbox One on launch but kept missing out on the PS4.
I was always going to get both eventually so I'm no fanboy of either.
The Xbox One had games I wanted.
Most of them were available on both systems, since I got the Xbox, I got them on there (Madden, NFS, ACIV).
Now that i have the PS4 on order (on a UPS truck now), I can't think of a game I want.
(of course I am an idiot for wanting a console with no games I want when I could have easily waited).
Anyway, via tips on this forum, I traded my ACIV to Gamespot for $40, I then bought the PS3 digital version and will upgrade to PS4 when it comes.
Back to your topic, Killzone is really the only option but I am waiting. It has discount written all over it,
Knack looks like a $50 tech demo.