The oldest game console I currently own is my Model 1 Sega Genesis. I do own a NES, however it's the Toploader version that was released in 1993 so it's not as old as my Genesis. My Genesis was manufactured sometime in 1991. It's the main Genesis I still use to this day and it works fine, funny enough it was a refurbished console too since there's a sticker on the bottom that says it was refurbished by Sega themselves. Well whatever they did to the console, it seems to have held up.
I actually use to own the Atari and original NES, (both were originally my fathers). I no longer have them in my possession. Though I am sure they are around somewhere.
For the oldest console I currently own in hand, it's the SNES. It's not touched much anymore as I own the switch that has quite a few games available through the Nintendo online subscription.
I think I still have a Super Nintendo kicking around somewhere but I have no idea where it is at the moment. I've never been much of a gamer but I liked playing Super Mario Kart and Tetris Attack.
I still got my original Playstation, which is most likely the oldest console I own (parents threw away earlier consoles that stopped working ). It technically still works, but sadly the disk reading laser died about a decade ago and I have yet to try and replace it, mainly due to owning a Playstation 2 which supports PSX games.