I think I'd like to expand on my post here.
I've easily spent the most time gaming on the N64 and DS; however, as I said, that's mostly because I was younger at those times - N64 was released during my adolescent years - when I had the time to play but also had ways to make money and buy my own games. DS was released during my early adulthood, and I bought into it shortly after the DS Lite released, so I had few responsibilities and tons of good games.
3DS probably got the next most play time from me, followed by Switch, GB/GBC, Wii, SNES, WiiU, GBA, NES.
However, Switch, without a doubt, would easily have far more game time if not for the fact that I just don't have as much time to play as I once did. Heck, 3DS falls into that same boat - I became a father when it was only a year and a half old, and now I've got two kids. Adulthood tends to restrict your ability to game like you used to pretty heavily.
Between the quality of the games it has, the quality of the hardware, and the flexibility of being a console OR handheld... if the kid I was when the N64 came out could've had access to a Switch, I may have never done anything else.