PS4: 4,480,444 (NA + EU, Global sales start until week 15)
XBO: 3,153,778 (NA + EU, PAL and JP don't start until 10 months later...but only a small boost)
Switch: 3,124,256 (Global Launch)
Wii U: 2,334,873 (Global sales start week 3)
3DS: 2,099,941 (Global sales start week 6)
Vita: 605,184 (JP only, Global sales start week 11)
Added the global launch tags to put things into perspective, instead of random number flying about. Also as much as people like to say it matters, a holiday launch does not matter. A launch is going to sell out of the hardware regardless and it's all about supply and demand.
Vita pretty much struggled until it started doing well in JP, and even then it still never took off. 3DS, XBO, and Wii U all share a similar story. They all did very well in the early launch window (IMO launch window is the first 3 months of sell), but fell off a cliff by their start of their 3rd month (Wii U fell into a bottomless pit). 3DS and XBO sales jumped when they had their price drops, Wii U could have done the same, but Nintendo refused to take another loss or break even on sales.
The 3DS vs PS4 vs Switch, will be the only interesting sales comparison, unless Switch suffers from the same nose dive in sales (which I won't happen due to Mario Kart releasing).
Based on sales now, PS4 is going to lead against the Switch:
*NA PS4 will do better in the long-term while Switch has small victories here and there in anticipation for big releases.
*EU PS4 will dominate like it's been doing already.
*JP Switch will dominate like it's been doing.
*RoW PS4 will likely dominate considering the PS3 beat not only 3DS, but Wii and squeezed a win against DS in RoW regions.
The real battle for Switch is the 3DS. 3DS Year 1 was around 13.8m, thanks to the price drop from $250 down to $169.