Wii. It has Xenoblade and Sin & Punishment Star Successor. So Wii for me. I like the DS a lot tho. 3DS is the biggest letdown of a handheld I ever owned.

As weird as it will sound I think Wii U is my favorite of that group.

I think Splatoon, Mario Maker, Mario Kart 8, Zelda: Breath of the Wild, Donkey Kong Country: Tropical Freeze, Bayonetta 2, Smash Bros. Ultimate, Mario 3D World, and Xenoblade Chronicles X, Pikmin 3 are better than the 10 best games on the DS, Wii, or 3DS. And it's not even particularily close. Wii has the two Mario Galaxy games, but it can't match up overall to that top 10 and when you consider the Wii U had a shorter life span ... 

I played *a lot* of Splatoon. Also HD at even 720p was soooooo much nicer than being stuck in the SD/sub-SD era of ugly Playstation 1 tier visuals (DS), Wii looked terrible on a lot of HDTV sets with poor scalers from that era, and 3DS was a bit better I guess but still kinda of a fugly system in terms of visuals.

I also loved being able to play virtual console on the Wii U tablet while watching TV, so I played a lot of Earthbound on it. Even stuff like Zombi U, Rayman, Batman: Arkham, Mass Effect 3, etc. were strong games. 

I liked Iwata's personality and I understand why they had to pivot at the time coming off the GameCube and given that Microsoft and Sony were spending like drunks, but I'm glad that era is over. Yamauchi era > Furukawa era > Iwata era for me.
I'm gonna be honest too, I didn't enjoy the 3rd party stuff on the Wii or DS all that much.

Personal taste and all, but I'd rank the likes of Xenoblade Chronicles, Twilight Princess, Skyward Sword, Metroid Prime 3, Monster Hunter Tri or Sin & Punishment Star Successor as just as great as say Mario 3D World or Splatoon or Pikmin 3.

I feel like the stereotype of Wii having no great games outside of the Mario Galaxy duo is a myth perpetuated by PS3/360 console warriors during the 7th gen.

I think the Wii, it left a cultural phenomenon like no other, the games were great.

I think DS is up there too, but I feel like the best games and experiences were more memorable on the Wii then DS. DS had more quick less memorable pick up and play games while the Wii had Nintendo games that were meant to be the forefront of game quality.