On one hand, Wii U is a brand new console. On the other hand, Xbox 360 has Halo 4 and a price cut.

Xbox probably. It's cheaper and has more games.

xbox

The 360 probably. It was a lower price, Halo, CoD fans, and some extra weeks to sell.

Xbox 360!!!

I don't think Nintendo manufactured enough Wii U's to outsell Xbox 360 in NA.

360.

WiiU will be supply constrained.

360 should be around 4.5 to 5m.
Nintendo stated they will only produce/ship 5.5m by March31. That means prior to jan2013, you should only expect 3.5m to 4m at the most available to sell.

EDIT: aaahhh just realized this was NA only. I was referring to WW.

For NA only, it should still be 360 easily with the same constraint on WiiU. out of the 3.5m to 4m, you can't expect more than 2m to be in NA, probably between 1.5m and 2m. 360 should be able to hit 2.5m to 3m in NA alone as US is 360s core market by a lot.

360 will win hands down. The software line-up is really good. However, although not a home console, the 3DS should give a run for its money.

What's the window?

3DS beat 360 last year and that was before 360 had a YOY decline in the double digits.

If you're including the 3DS.... then there is no way anything else will beat that. You have to realize the 360 is down by over 20% YOY and the 3DS is up by over 40% YOY. Last xmas 360 sold ~7m and 3DS ~7.3m. This year 360 should be around 4 to 4.5m and 3DS should be 8m up to 10m.

3DS>>PS3~360>WiiU>>DS~Wii~PSV>PSP for this holiday... easy.

EDIT: aaaahhh. Just realized this is NA only. I was referring WW. :(