I do recall this now that I randomly look at this thread again, but Archangels do have a better cost:damage ratio than Light Dragons.
6:7 compared to 13:12. Light Dragons have a negative ratio, and Archangels have a positive. I would rather pack them for this reason, as well as for their healing against Pandemonium/Plague (which two Elders have). Would do -1 Tower, +1 Angel for that modification.