Wii for many reasons....
Wii U for Breath of the Wild

Wii could play Gamecube games. And, what games came out for the system at the time matters way more than backwards compatibility anyway. 

Mario Galaxy I & II + Xenoblade make me think overall the Wii was better.

Its crazy how important just a few games can be on a nintendo system, granted those 3 are amasing games.

That and also how many let downs The Wii U gave us:
Animal Crossing: Amiibo Festival (who doesnt want a low budget rushed board game to push amiibos?)
Devil’s Third (buggy mess)
Paper Mario: Color Splash (nintendo what have you done! to my paper mario!)
Star Fox Zero + Star Fox Guard (they butchered it to try out the multiple view point thingy)
Super Mario 3D World (stinky 3D mario compaired to others)

I enjoyed the Wii a lot with my siblings and friends and even my parents!

I tried the Wii U once at a Kiosk and have never seen one again...

I chose WiiU, because it has two of the best video games ever made - Mario Kart 8, and Breath of the Wild.

Wii got really fun with the Wiimotes Party games, then Just Dance and Smash with friends, after that, Other M, Mario and Zelda games! But the most important thing to me was the epic Xenoblade Chronicles Game, that game made me change my life's Goals and will to be a better person.

I liked Wii a lot more overall.
It was slick, fast, and sleek. It had a lot of charm with the channels as well, and the little online shows it did to promote upcoming and previously released games.

The Wii U was slow, convoluted, and bulky (not just physically in size, but its UI was bulky and convoluted) and there wasn't really much entertaining about it, it was mostly harder to get around... It had Miiverse that was so slow it wasn't worth it.

The Wii also had a significantly more entertaining library. About the only thing the Wii U had on it were the two Nintendo based open world games like Xenoblade Chronicles X and Zelda Breath of the Wild - which to be fair people would much rather play on the Switch... oh, and there was also Earthbound on the VC.

The Wii had a few VC games the Wii U didn't have that were key, including Chrono Trigger and Final Fantasy 6 - but when you measure the sheer volume of VC games, the Wii really dominated in that area.

The Wii had a lot of party games (Smooth Moves, Guitar Hero, Rock Band, Just Dance, etc...) which I played the hell out of.
The Wii had the first modern Mario Kart game. and while Mario Kart 8 was even better, the second really modern feeling Mario Kart game spoiled us with handheld mode and
8 player multiplayer which MK8 on Wii U lacked (unless you wanted to play online, but Mario Kart online is a shadow of 8 players local); Mario Kart 8 became great on the Switch because it had 12 player local.

There were a lot of really great creative games on Wii that I enjoyed a lot:
Rune Factory Frontier
Little King's Story
Muramasa the Demon Blade
Elebits
Endless Ocean
Zack and Wiki
Kirby's Epic Yarn
No More Heroes
Super Paper Mario

It had the open world games as well:
Scarface: the World is Yours
Godfather: Blackhand Edition
Bully
Driver: Parallel Lines

It has the big games:
Resident Evil 4
Legend of Zelda: Skyward Sword and Twilight Princess
Super Mario Galaxy 1 and 2
Monster Hunter Tri
Xenoblade Chronicles
Mario Kart
Smash Brothers Brawl (sorry, the Wii U was kind of lame outside of adding Cloud)
Tiger Woods PGA (back when golf games were actually good)


I'm a little biased toward the Wii mostly because I played it more than any other console I ever owned during its own generation (in total, it probably falls into third below PSX and SNES), and to be honest - I probably played actual Wii U games about 250 hours total, and 150 of those hours were Xenoblade Chronicles X... I more than likely played old Wii games on it more than Wii U games because I transfered all my data over (which I regretted doing).

I also see the Switch as the proper successor to Wii. The Wii U focused too much on the one "You" and was a piss poor console for local multiplayer games compared to Switch and Wii. The Joycons are much more a successor to the Wiimotes than they are to the Wii U Gamepad. Also, the hybrid nature of the Switch is a significantly better idea than using the a screen as a controller - I think that's what was intended with the Wii U, but they realized the technology wasn't there - so they changed a thing slapped on "Hey! assymetic gameplay" and tried to sell everyone on an ugly looking half-baked console. Looking back on it, Nintendo would have been significantly better off without the stop-gap Wii U, focused on Wii development until the proper successor with the Switch came out later... which looks like it was Nintendo's plan all along, but couldn't get out on a timeline to please shareholders.

Wii. Wii U had a chance because its concept was great. However, Wii was just incredible.

The Wii, duh. Wii U was just Wii HD with underpowered hardware and none of the magic that captured the world the way the Wii did when it was originally released.

Didnt OP made before similar thread/s!?

In any case, for me personally Wii U, it had more core Nintendo games that I was interested in, Wii had too much casual games for my taste.