Charlaquin
Goblin Queen (She/Her/Hers)
Dominaria is the easy choice for me. Lorwyn/Shadowmoor would be a good one too.
I think Mirrodin would be a pretty cool setting, but New Phyrexia sounds pretty much like doing a Baa’tor campaign setting, but with a machine aesthetic.. Mirrodin/New Phyrexia would be a decent setting as well.
I'm sort of surprised they haven't done Strixhaven yet.
A Transformers/Kaladessh crossover!!! (only I was kidding).
I guess the next will be Innistrad, and some day Eldraine, and later Kaldheim.