I will buy the PS4 when I get some extra money, I sold 5 years worth of vacations not taken last month (it is something called Prize Licence that the public servants have here in Brazil) and I am waiting for them to pay, cold take a wjile, like 6 months or so.
But, then, I will find a store that sells an imported PS4, will not pay R$ 3.999.
Or, I will wait for reports of people importing themselves, if it is safe (from Amazon and such), I will do it too.

The Xbox One I will buy if the exclusives justify it, like ten amazing exclusives that appeal to me, not Halo. Probably by the end of 2016.

The WiiU is the same deal, will buy it if they have crazy good exclusives. Probably 2015.

Wii U - Already Have One

PS4 - When Mirrors Edge is Released

Xbox One - Meh probs never.

Wii U: Already got one (back in August)
PS4: When it gets a decent amount of games I want for it. Right now it stands at 0 so I'm guessing somewhere in early 2015.
XBox One: Probably never, although I really wanna play some Killer Instinct.

Wiiu - own (since launch)
3DS - own (since launch)
Vita - owned (bought at launch and sold it a few months back)
PS4 - at Launch (mostly for my sister)
X1 - at Launch (mostly for my girlfriend)

I already have a Wii U, and can't wait for Super Mario 3D World!

PS4 - Maybe in the future, when the there's a price drop. 

The soonest I'd get a PS4 would be for Second Son. But I think I'll wait for a price drop. None of the launch titles appeal to me, and I want to build a new PC anyway. I won't bother with the Wii U or Xbox One, and the PS4 will probably be for exclusives only.

I bought a Wii U at launch and learned a painful lesson.  Don't buy a console until there are at least three games you want available .  Now I am glad I am a Wii U owner, but it took a year.  

Between the PS4 and XBox One, I will probably lean toward a PS4 since more RPG's tend to be released for it.  However I am going to wait until a few of them are out before I make a choice.  I don't see myself buying either for two years.

I purchased a Vita post launch when there were enough titles available that I wanted.  I probably will pick up a 3DS XL by the end of the year since Bravely Default is coming out in the west along with Zelda: Link Between Worlds.

If the recent reports of PS4 glitches are no higher than normal for new e-products then I'll be buying around the time Second Sons launches. If the PS4 glitches turn out to be quite extensive then I'll be waiting until 2015 most likely, and hopefully a $50 price cut too.

Not getting Xb one or Wii U.

I want idt bad and have money saved for a PS4. But, I do not game as much as I used to so I still got a lot of games to play on my 360. I will wait for better hardware. I do not have to play the new Ass Creed on ps4. Basically, I will buy it for Infamous: Second Son and The Witcher 3.

Titanfall will be on my 360 so I have no problems not getting the Bone for many years after launch.

The Wii U I will buy in 3-4 years. Maybe

I'll probably get a Wii U next year. I'll need one to play either X or a new Zelda, whichever comes out first.