So, at the end, Splatoon will outsell Halo 5. HANDS DOWN!

[PAOerfulone]

Just did a bit of math with the numbers posted for the 5th of December. (Thank you, Machina!)
Splatoon:
USA - 109045
Europe - 50450
Japan (Media Create numbers) - 35256
Total: 194,751

Halo 5: Guardians
USA: 105924
Europe: 72597
Japan - .... Um, let's say about 1000
Total: 179,521

So with those numbers, Splatoon's 194,751 > Halo 5's 179,521.

Adding those numbers to their lifetime totals as of the 28th of November, we've got:
Splatoon: 2,960,308
Halo 5: Guardians: 2,582,176

If these numbers are true, (Waiting for January NPD)
Splatoon reached 3 million first... and Splatoon's chances of outselling Halo 5, lifetime, are getting higher and higher.