As someone said before, it's full of drama. They all seem to have their dramatic times, Armstrong is just the most obvious about it. Heck, his whole family seems the dramatic type, Catherine, His dad (especially this one) mom and Olivier, but she seems to hav a more subtly way (at least then her brother) at starting a scene... Actually it seems every time we see her she starts a scene...
Anyways, after Armstrong you might guess Hughes, because of his gushing on about picture and family.. Other then that I don't really find him that dramatic.
Even Riza is a bit dramatic, though she doesn't often start the scene she participates wholeheartedly in it. (Plus her seemingly undramatic way of telling Roy that he's useless, its one of the most famous quotes and ideas in FMA)
For the least dramatic.. I would probably say... Gracia or Sheska..they don't bring that much attention to themselves.
Look at me, trying to bring a old thread back alive.