Nintendo exclusives of course: Super Mario 3D World and DKC: Tropical Freeze were my main reasons and I added Pikmin 3, Mario Kart 8, Wind Waker HD (free download) and the NSMBU+NSLU bundle later. Bayonetta 2 will be next.

I also have Nintendo Land and Zombi U, but these aren't really my cup of tea.

Multiplatform games I prefer on my faster systems (PC + PS4).

I really liked the idea of the hardware itself, but I did make a list of titles I really want(ed) to play on which I decided the console was worth it.

Those were:
Xenoblade Chronicles X
Bayonetta 2
Pikmin 3
Wind Waker HD
Super Mario 3D World
DKC Tropical Freeze
Deus Ex HR Director's Cut (yes, really)

Considering some other retail titles, games on the eshop and VC, the list of good games to play seems to run a few dozen. If you add games for the original Wii, it's at least a dozen must plays.

Because its Nintendo, i always buy Nintendo and i know im going to get a quality gaming experience, the Wii U has delivered just that. A brilliant console that is criminally under rated.

Access to Nintendo's games

Nintendo games in HD

Price, it was the first one to reach my breaking point 250 U$ without a game or 300 U$ with a game that I want
Games, I really like Nintendo exclusive games as they offer good gameplay and it has enough now to interest me
Free Online, I really don't want to pay for online as it is something that I don't do very often anyway
Backward compatibility, I still have a few Wii games that I want to play and the control compatibility reduced the price to play with my friends

http://gamrconnect.vgchartz.com/thread.php?id=175769

I ended up just buying it for her.

Free online, and because I got tired of MS and felt like I missed a great deal of Wii games.

Nintendo exclusives XD oh and bayonetta 2 since the hack and slash genre is near dead.

Because every gen I have the most fun and memorable experiences from Nintendo games.

The sad reality. Ninja Gaiden's popularity and quality has nosedived, and Capcom (in saying they aren't going to make sequels to games that don't sell 2 mill +) have pretty much confirmed DmC is dead. Maybe The Devil's Third and Bayo will bring some love back to the genre.