The Legend of Zelda series. Particularly The Wind Waker. That's my favorite in terms of Nintendo games.
Too many to count, but here are a few: Super Mario World was the first platformer I not only beat but also 100% completed; Tetris was the first handheld game I ever played; Disgaea for introducing me to my beloved bane - strategy-RPGs; Fire Emblem 7: The Blazing Blade was my first owned handheld game; Cuphead for being a celebration of the Golden Age of Animation Pokémon Sun and Moon for reviving my hope in the Pokémon franchise (outside of the anime) (though UltraSun/UltraMoon did, unfortunately, break some of that hope with the changes they made to the story...)
Super Mario Galaxy (1&2) are mine. Some of my favourite games of all time. Loved everything about them.
Okay so I'm a big fan of the Xenoblade series, and I mean a BIG fan. Emotional involvement included. I just wish I could've played the Xenogears saga as well, but alas, I do not have the consoles nor affordable access to the games...