Wii
As an employee of Gamestation, I plan to analyse with keen interest the battle of the masses as they fight lock, stock and barrel to purchase Christmas console goodies.
I have a feeling the Wii is going to do rather well this Christmas. Not only does it have the largest target audience out of the bunch, but it is not over-priced, comes with everything ready to play in the box, and you won't feel like you're carrying a housebrick whilst you're finishing off your Christmas shopping.
Add to this the fact that the main reason most people buy Christmas presents in the first place - yes, kids - it'll be a no-brainer to opt for the Wii or DS, consoles which are not only innovative, but are fun and can even be educational.
Of course there are going to be serious gamers, parents, friends or partners buying for their teenagers or older children/friends/other half, who will opt for the PS3 or 360. People are often more inclined to spend silly money in the festive season, so I'm sure sales of the 360 and possibly even sales of the PS3 - if indeed a further price reduction is executed - will be fairly safe, although when it comes down to the crunch, I'd say Nintendo is in for the win.