Same dilemma in this house. 7yo girl, 5yo boy. I have a ps3 (untouched & no new games since I had kids) which the kids struggled with last year so I bought a second hand Wii for buttons with all the usual Mario stuff and the kids were obsessed.
Playing the Mario games has tought them how platform games work and they’ve both migrated over to the ps3 now. Minecraft & lego games mainly but they do play a lot of other stuff I’ve downloaded free from PlayStation plus over the years
We were going to get a Switch but my wife asked both of them off they prefer the Wii or PS3 & the PS3 won. We’re getting a PS4 as we think it will have much more longevity and far more games than the Switch with the added bonus that me & the Mrs will use the PS4 too.