Well, it seems the Xbox One has recently sold out on Amazon. However, it wasn't enough to push it over the launch edition of the PS4, which still rests comfortably at #3 for the Best Sellers of 2013 (So Far). The Xbox One was able to end up at #6. Of course, what's quite impressive with the PS4's position is that on Amazon, the PS4 was split up amongst several SKUs, while the Xbox One only had 1 SKU. Some of the PS4's other SKUs have broken the Top 100, as well. The BF4 bundle currently sits at #92 (#91, now). The Watch Dog bundle sits at #77 (#68, now). And while the Standard Edition currently sits at #66 (#40, now), it is still available, so it will most likely be heading up the list quite quickly.
Many may remember that in late June, a Gamestop memo was leaked that stated that Sony basically told them to open the flood gates for preorders. Even with a seemingly endless supply, the PS4 has already sold out of every one of its SKUs on the Gamestop website. On the flip side, Gamestop was warning stores to not take more preorders than they were alotted for the Xbox One, due to limited supply. It seems that even with this limited supply, Gamestop has still not sold out of Xbox One's online. I think it's pretty safe to assume, the PS4 is going to greatly outpace the Xbox One in Gamestop sales.
On a related topic, if one were to look at Amazon UK, the PS4 is also #3 for Best Sellers for the year. The Xbox One, on the other hand, is only at #44. I think it's safe to say that the PS4 is going to enjoy a very good launch in the US and the UK, two Xbox strongholds of last gen. I think Sony is about to take back the US and the UK. What say you?