The one on top should be the one you are most proud of getting or the most recent. When in doctors/dentist offices my sight is automatically drawn to the top frame(s)

good point ! thank you

-- There are no "rules" about the orientation of framed degrees hung on the wall. It all depends on the wall space available. If the space is tall and narrow, that is the way they should go, etc. Take a look at the shape of the wall and hang the degrees, in similar frames, in a way that follows the lead of the wall space. Keep the grouping simple so the focus is on the degree and not in some tricky wall arrangement.

I prefer them hung with the centers aligned, either horizontally or vertically. :) No matter the shape or orientation.