Hotels in Japan are different from most countries in that they are very service oriented and status conscious, but that status is more determined by the room category that you book rather than being Platinum or Diamond. Hence the problems people have with room upgrades. I'd check what level of room those rates are for at each property, and pick the one that is highest from the bottom. I'm not familiar with that Hilton but I expect the Sheraton is a nicer hotel and has better rooms.