Switch on its own with the ability to play a lot of games from the other combinations is probably the option I would recommend.
Buuut, I enjoyed gaming the most in the Wii - DS era. And a lot of games from that time is not playable on the switch. The DS strange design gave way to a lot of unique games that does not port over easy to systems of another family. And even if the Switch probably could emulate Game Cube and Wii games, so far it does not.
Pretty much anything on earlier systems and from WiiU is playable on the switch.
The only other real contender is the 3DS -era (WiiU not worth mentioning) but I never liked the 3DS much but at least it brought some unique experiences with the 3D.







