This just isn't gonna work, we need to see YOU in those dresses.
But out the top of my head, #6 is really classy and suited for a graduation.
I think #5 is pretty good, I like girls that aren't afraid to be casual and sometimes that can be a great hit.
#2 is the worst if you ask me, I don't mind red but the upper part of the dress is too simple and doesn't go well with the lower "wavy" structure at all. Stay away from that.
You can call me Valery from this point on.