I’ve ruminated over this all week and like many others have struggled to limit to 3.
If pushed, I’d probably include Italian and Japanese for their breadth of cuisine, there are so many regional and sub-genres to never get bored. After that it gets very tough, but I’d probably pick one of Spanish, Indian, Thai or Middle Eastern/North African.
What surprised me is that despite loving French food and wine, it doesn’t get a look in.