The Switch, without question. No Nintendo hardware has ever been more versatile, more adaptable, or had more potential. It is easily recognizable, lightweight, portable, and just downright beautiful. The sound it makes, the joy of watching the handheld display instantly transition to the tv display, and the beautiful cases it fits so nicely into create such a pleasing experience.
If I had to pick a runner up I'd probably go with the WiiU. I just loved the tablet design, the compact and roundness of the WiiU itself, and the fact that it doubled as a Wii.