Assuming I'm remembering how they lined up in the playtest correctly:
Heavenly covered LG planes (Arcadia, Celestia, and Bytopia)
Idyllic covered NG planes (Bytopia, Elysium, and the Beastlands)
Exalted covered the CG planes (The Beastlands, Arborea, and Ysgard)
So archons, being LG and native...