I recently dusted off an old N64 to introduce my son (4 years old) to video games, figured Mario Kart 64 was my own introduction, and it's simple/easy enough to play. After about a week of playing an hour a night he's getting the hang of it. It wouldn't run on our newer TV in the basement, which didn't have the red/yellow/white RCA inputs, so I had to run it on the living room TV which is older. Otherwise, it still works great and is just as fun as ever....
We have a PS4 (and a 3) and Xbox 360 that haven't been touched in years - too complicated for the little guy at this age I think.
Mrs.Firm has a Switch, which she plays quite a bit, I've never touched it....controller setup seams really weird to me.
The upcoming Grand Theft Auto is about the only game I have any interest in at this point, so when it comes out I'll invest in a PS5 just for it.