None. Even with it's horrible year in 2013, it only dipped below 20k once. And it was in june. This year, there's mario kart 8 and donkey kong for the first half of 2014. And I just can't see xbox one dipping below 20k.

What did WiiU have between February and late May last year (I'm not sure).

Do you not see a drought second year running really badly affecting sales?

I don't think either will, to be honest. Wii U will be closest for sure though; I can easily see below 25k. Then again, I wouldn't be shocked to see it briefly dip below 20k either, the summer months are cruel to most consoles.

I say the Wii U because they will have a drought of games in the next few months while the X1 still have games coming out.

I'm not sure either will go that low, though both are in trouble. If I had to pick one it would be One, mostly because of price. Wii U will probably be "OK" with its low price and MK8 coming out.

Worldwide ? WiiU obviously, nothing relevant in sales between DK TF and Mario Kart 8, 3month and 10 days.

One will get Titanfall, and some relevant multiplatforms.

edit  : and dont forget Kinect Sport Rivals on One ! Huge potential on casuals

Nintendo wishes they had Microsoft's "low sales".

Last year, wiiU had basically no major game releases from Jan to july. There were a couple third party games which all bombed, lego city (which was also released on 3ds) and that wario game (which also bombed). 

Basically, no significant releases in the first half of 2013. Mario kart 8 alone will provide a much bigger boost then all of these games that I mentioned combined. There is also DK which should do very well here in the Americas and should also do decently in Europe. 

To answer to your second question, yes, that 3month drought will affect sales but not enough to make the system dip below 20k. I predict that 25k-30k will be the worst week for wiiU in 2014. 

The X1 will stay afloat with all the third party support it's getting. But it's kinda looking sticky for the Wii U.

WiiU.

XOne is not doing very well right now, but I sincerely doubt Microsoft will allow their flagship console to go down easily.