I wished we could have some worldwide numbers or at least estimates to see what happens. Who near or far they are from each other.
Well, we can come up with a decent estimate at least. First, the launch-aligned worldwide shipment figures:
Wii U Shipments to Retailers:
4 months, 14 days - March 31st, 2013: 3.45 million
Xbox One Shipments to Retailers:
4 months, 10 days - March 31st, 2014: 5.1 million shipped
Now, the sales to consumers for the U.S. alone in that same period:
Xbox One [NPD through March 2014]
LTD: 2.53 million
Wii U [NPD through March 2013]
LTD (at that point): 1.08 million
So we can see that Xbox One has sold 1.45m more consoles in the U.S. than Wii U did in the same period. But if you look back at the first set of numbers, you'll note that worldwide, they've only shipped 1.65m more consoles than Wii U did. In other words, it seems that outside the U.S. Xbox One sales to consumers are at best only 200k units ahead of Wii U launch-aligned. (This is the maximum possible gap--if any of those 200k units are shipped but unsold, the true difference is lower.)
But this is misleading, because Wii U launched in more markets than Xbox One. So we have to increase the gap, either by adding the hypothetical number of Xbox Ones that will be sold in the first 4.5 months when it finally releases in those countries, or alternately by subtracting how many units Nintendo did sell in them. We'd essentially just be guessing at the former number, but we can make a better-supported initial stab at the second.
Wii U's biggest unopposed market, Japan, is known. By the end of March 2013, Nintendo had sold to consumers ~861k units. This gets our "Outside the U.S. and Japan" sales gap to ~1m in favor of Xbox One. But there's still more Wii U-but-not-Xbox countries that would also add to the total. These are individually pretty small markets, but summed up they'd have a non-negligible effect on our estimate. Unfortunately, the remaining regions are mostly black boxes, with no country-by-country breakdown available to us. All we can say is that the final number will be higher than ~1m.
To sum up (all launch-aligned):
Outside the U.S. and Japan, Xbox One has outsold Wii U by more than 1m units.
- In the U.S., they're beating Wii U by ~1.5m, a very large margin
- In Japan, they're losing by ~860k, a very large margin (due to not launching yet)
- In some countries, they're losing by small margins (due to not launching yet)
- Where they've launched, they generally have beaten Wii U by small margins