Armin is a smart fifteen year old kid, but without Erwin, there is no Survey Corps.
Erwin is, of course, the more valuable of the two characters, which is why Levi knows immediately which one to save. Armin can't possibly stand up against the political forces inside the wall, nor can he be the one and only leader who can move the world.
Armin should be saved. Erwin must be saved.
"but without erwin there is no survey corps."
erwin's appointed hanji as his 2nd in command so i'm pretty sure the sc would still survive, sure they'd suffer a great loss but they'd still have hanji, levi, eren, armin, jean, and mikasa so...
Erwin please speak up and order to give the serum ti Armin
be a wise captain