This one is a no brainier purchase at this point in the PS4s life. The 1st truly next gen game. Killzone, Forza and Ryze were launch titles and were not as polished as the next wave of games will be.
End of 2009 Predictions (Set, January 1st 2009)
Wii- 72 million 3rd Year Peak, better slate of releases
360- 37 million Should trend down slightly after 3rd year peak
PS3- 29 million Sales should pick up next year, 3rd year peak and price cut