People need to drop the 'multi-plat versus exclusive' argument, given that watch dogs outsold mario kart 8 on ps4 alone, not to mention that the xbone version also sold more in the us and the uk.

WD was more surprising. The US PS4 sales are the big one. I guess people really didn't have that many games they wanted to play until this one, because they came in droves week 1.
I expected this amount from MK.

But why really compare them so much?

I'd say MK8. It sold 1.2 million on a struggling console in 3 days. And yes WD isn't in Japan but WD is a very western game so Japan won't really buy WD. I know MK isn't a new IP but MK8 was predicted to sell very little. I think both are impressive though. Remember that we don't want any console to sell bad or It will just hurt the industry. We want everything to do good since this is "the last generation of gaming" as many people claim.

Ok, Watch_Dogs might be a new IP but there was a huge marketing effort to support it that seems to be just as expensive as the game itself. It was hyped to the stratosphere and it's not like it's an indie title.

Watch Dogs is way more impressive, new IP.

Considering that WD is multiplatform, on platforms that have FAR, far higher instal bases than Wii U? And MK8 is only on Wii U, with a still relatively small install base? The answer is yes: MK8's numbers are, in point of fact, more impressive. There really isn't much of an argument to be had on that.

Yes. But WD is a super-hyped game, releasing on at least one super-hyped console (PS4), along with one kinda-hyped(?) console (Xbone), and three very high install-base platforms (PC, PS3, 360). How is that impressive, when it's another GTA clone, made by the makers of the uber-popular Assassin's Creed, and the game itself has been (over) hyped for the better part of two years now? Of course WD's numbers were going to far higher. Gamestop's pre-order bonuses alone were going to insure that a couple million of the usual GS pre-order customers were going to get it.

So I'd say MK8's numbers, considering everything that has gone on with Wii U in  the last year and a half, has to be considered more impressive.

Watchdogs. It did great considering is  new IP and the negative press that it received for its downgraded graphics.

Both did great but I can't decide, especially WD had a few more days to sell than MK8.

I think Wii U hasn't reached much of the masses so has a concentration of big Nintendo fans, so kind of expected to have a high attach rate.

For WD, I think it shows how hungry people are for more games on PS4/XB1 right now.

From counting?  The PR from Nintendo included the full weekend, Media Create/Famitsu numbers go through the 1st, VGC numbers go through the 1st (in Japan).

29, 30, 31, 1.  Four days.