I own both systems and will be playing Destiny (as well as any serious FPS game) on my XB1. If it had to come down to one thing, it would be the controller. The PS4 controller, while better than the PS3 controller, is still miserable to use compared to the XB1 controller. The PS control sticks are just so clumsy and imprecise. My thumbs are constantly sliding off of them. Doesn't feel natural at all. I guess the other reason is the strength of XB Live vs. PSN. Just feels so much more user friendly and stable. Don't get me wrong, both systems are great and have different strengths, but Destiny on XB1 was a no-brainer for me. PS exclusives be damned!