#3 The Planet's Champions retain
No matter how it happens, the best possible outcome for this showdown is for the Planet's Champions to win and retain their titles. They recently won the belts and deserve a good run for saving a division that was left in shambles. They were going along as a part of Shane McMahon's tyranny, so if they drop the belts right away, it was weird to crown them in the first place.
Heavy Machinery is still new to the main roster whereas both Rowan and Bryan are veterans. Rowan has won the titles with different partners, just like Bryan. They are a great heel act that is unlike any other on the roster.
Bryan is likely staying away from the WWE Title picture since he lost it to Kofi Kingston, so the best use of his talents now is in the tag division. I foresee a match for the titles with the New Day at SummerSlam, so to get to that point, the champs retaining is the most logical finish.