Myself I found a good deal on one and it was mainly because I wanted to play sm3dw and other exclusive and its a console that I knew my kids would enjoy.
Afterward I found that I really like it myself, love the gamepad as its great for netflix and browsing the internet, the game roster on the console is amazing, lots of must have games and it keeps me happy. Basically we are always using the WiiU, whether its for playing games or watching netflix etc. I can't say the same about my PS4 which is collecting dust but I mainly use it to play blurays.

I originally bought my WiiU because I simply wanted to have the console as soon as possible! I should have waited until 3D World's release though...

I waited until Mario Kart 8 was released then I purchased the Mario Kart 8 bundle. Also, it's backwards compatible with Wii games and I still love to play Mario Kart Wii. Another thing is free online play and gamepad controller with off tv play. Nintendo's exclusives are awesome as well!!

I traded in my PS3 and got it for pre-order when it was available because the moment I saw Pikmin 3 I had to get one. Getting MH3U was another great factor and I was also just wanted the next Xenoblade game as well. Lots of great games and can't wait for Bayonetta 1+2 next week.

For two reasons:
1.) The games (both Nintendo and the little bit of 3rd party support they get)
2.) Nintendo is the last console maker that wants to offer a unique console experience. PS4/Xbone are PCs that you plug into your TV, PCs are PS4/Xbones that you plug into a monitor. Boring.

50% Hypes 50% knowing I will enjoy the games

Wii U has so much potential it's not even crazy. For all of the exclusives Nintendo represents and hasn't seen in years (F-Zero, Metroid, Star Fox,) this could revolutionize and reboot its sleeping exclusives. I got a Wii U practically because I believe in Nintendo that we'll be getting bigger and better things in shorter time. Games like Smash and Splatoon has hit it home for me.

Only console that plays Nintendo games.

I bought it in January for 3 reasons.
1. Played a world of SM3DW over Christmas with friends and it was a blast.
2. I wanted the WWHD bundle with the decal-ed gamepad because I'm a huge WW fan.
3. I could do off TV play for both old Wii and new WiiU games. I'm in college and in my second year I still don't have a TV. I wanted to remedy that but no one else in my apartment wants to use a 1080p TV in the living room. I need some gaming roommates.

I knew at the time that there were other games planned for release, so I was excited for MK8, X, SSB, Zelda U, and SMTxFE. And I wanted Pikmin 3 from the backlog. And I hoped they would do a bit more interesting things with asymmetric games, though I'm pretty sure that won't happen at this point. I've moved into the indie scene for that.

After picking up the console I decided it would be great to have Rayman Legends on sale and Bayonetta took me by surprise, and so I'm glad to have a WiiU for those. I'm also waiting for Captain Toad and Splatoon now. Maybe Yarn Yoshi. When I bought it I was hoping there would be a few games I didn't at first know I wanted, like these.

1.) It has lots of games that DON'T include shooting things with guns and dark, mature themes. I really got tired of the overuse of guns and murder in games over the last decade or so.

2.) It's a traditional console.

3.) Free online gameplay.

4.) It's BC.

5.) It's totally fresh. While the other two consoles are just beefy versions of the PS3 and 360, the Wii-U is a completely different experience from that of the Wii. 

6.) Nintendo IP. Can't play Nintendo IP without a Nintendo console.

7.) It's family friendly which means you don't have to exclude your mother when she comes to visit or your 5 year old cousin.