Interesting fic, and my votes, aside from Pansy and Luna, would be Hermione and Susan Bones, as the four of them would be best for Harry imo. Now what will that mean away from Hogwarts or after the war, will that be permanent, or just a temporary thing?
Author's response
It would be permanent. Harry is the head of several families, so his options are to have multiple kids with one wife and pass the titles on that way, which isn't very common, or to have one wife for each title and get heirs in that manner.