For me it's the (New) 3DS. It's about the peak for handheld gaming. It can run GB, GBC, NES, SNES very well, GBA can run natively and obviously DS/3DS. You can run pretty much any Zelda game up to the GameCube on it with the official ports of Ocarina/Majora. The emulation community also has some promising demos of Wind Waker and Twilight Princess, but who knows about that. I have a Switch and it's frustrating seeing games that Nintendo haven't released for it (like WW and Pokopia), but maybe after a decade I'll get a Switch 2 OLED whenever that comes out.