For me, it is the Gameboy Advance SP. It was the 1st Console that I ever owned, until I got it, I just played PC games. I didn't get into Console gaming until a little later in my youth. I did play the Nintendo 64 and Gamecube at other friend's houses until I got my own Gamecube.
The 1st game I got with the GBA was Metroid: Zero Mission, and it's because of this game that I grew to love the Metroid series and other Metroidvanias overall.
This might be cheating, I don't know if it counts, but I do own a SNES Classic. The SNES is older than the GBA naturally, but because the Classic version was made around 2017, it might be considered newer since it's effectively making it so that a great selection of SNES games can be played easily on modern TVs.