It's got to be...
The Wii console, although I have one myself I still think that the Wii console will be the one to outsell the other consoles during the festive period.
Nintendo have always gone for the niche approach, they have never gone all guns out with the hardware and the latest technology... but they have nailed on the head an area of the market never really explored by Sony and Microsoft.
I have had both Xbox and playstation consoles in the past and while they did provide great visuals in the games for their times, I still found myself going back to my PC to play more interactive games, games that you can download mods for to change them and keep them interesting.
Sony and Microsoft are both gunning for the Hi Definition and rich graphic-intense games, and both supporting the next gen video formats, but with the games, people will again play them till they have had their fun, and at £60 a game it's going to burn a hole in their pockets quite fast...
Where as with the Wii, they have an innovative controller, great selection of current games out plus the added bonus of being able to run gamecube games (which are cheap as chips second hand) and the biggest bonus (in my opinion) is the virtual console, bringing back old classics like blazin lasers and super mario brothers etc... even though they are a small price to pay for they provide hours and hours more entertainment, and the Wii can download additional applications to go along with the news reader and weather channel etc... over-all it's a more interactive console and when the online games start flooding through will bring even better gaming experiences to people.
And as for sales, I was amongst the first in my workplace to get a Wii, after showing someone just for 5 minutes they got one, then another colleague had one and another etc... it's like an infection allbeit a good one :)