The Hilton Phuket is a hotel for tourists with many guests from China and Russia and families. So it's not a really quiet and private property. In the Lotus Wing noise appears to be louder than usual. As far as I remember, it's not about the noise coming trough the wall, it's about the noise coming through the door of your room.
Anyway, it depends on the occupancy if you have a choice or not. The hotel has the right to upgrade you, as long as it is really an upgrade. The genereal Diamond handling there is not really good. They don't think too much about your stay.
If I were you, I would take it like it comes. There is no clear winner with your priorities from my point of view.