i have both. i didn't turn on my ps4 for about 2 weeks after i had my xbox1, but i only have killer instinct on xbox1. i finally turned on my ps4 on a sick day to finish knack (had about an hour left on it), and tried to give killzone another play, but got to chapter 4 and that game just bores me to death.
i'm not sure when the next time i'll turn my ps4 on will be. i can tell you that tonight i will be playing killer instinct though.
next game i get might be that tomb raider game, but tbh i'm not sure what system i'll get it for, if i do get it.
i also didn't have my kinect hooked up, but i hooked it up (and kept it in my a/v closet) because for some stupid reason, it's required for upload studio.