To all those people noting that ps4 has more preorders on amazon, that list is refreshed hourly, and is therefore true for only that hour.
If you dig a little into the best sellers archive of 2013:
http://www.amazon.co.uk/gp/bestsellers/2013/videogames/ref=zg_bs_tab_t_bsar/279-2285307-5597923#5
The xbox1 is 69th way ahead of the ps4 in 91st position.
(only checked the uk)