I'll chime in as a primarily a PC gamer.
First, you have to ask are there any exclusives for each system that are very important to you (Halo vs Little Big Planet, Shadow of the Colossus, etc). If not, then the decision is very simple.
Both systems will by and large have the same games. Therefore you want the one which is more powerful and that's the PS4.
Lots of games that run at 1080 on the PS4 have to be downgraded to 900p on Xbone. The same issue remains for framerates, textures, etc.
Though on a personal level, I prefer the Xbox's controller over the dualshock.
Addendum: If you're looking into modding and getting pirated games, then I really don't know, someone else can guide you better on that level, which system is easier to work around.