i think the epic bases are more directional, i.e. have a clear front and back. from a distance it easily identifiable. just like torpedo markers.
from a distance the square chits for ac can be confusing to me as to which way they are facing as there are now 4 equal sides.
i understand this is subjective and thus think we should allow both.
i am all in favor of stacking, and if this comes to pass, would make the square ac markers easier to manage. models can still be used to be the topmost chit, with increasing size of the wave denoted by how many chits lie underneath the model. while functional, i believe this is less aesthetically pleasing. a problem might be though is what would you put as the top marker. in a mixed wave, do you always put the fighter chit? the chit representing the most numerous in the wave? what if it is a tie in fighters, bombers, and assault boats? it could get problematic.
i think the best visual would be to denote the size of the wave based on the number of models on the marker. and as a complementary benefit, denote the content of the wave based on the actual models used. 4 attack craft models will easily sit on a 2cm x 2cm chit; and readily on the epic base.
the compromise and alternative solution to stacking, as i suggested previously, would be to limit how wide a wave can be, regardless of the size of the marker used, to be no more than 8cm wide. this would have minimal impact on the game as the standard carrier has 4 launch bays. when using 2x2 markers, the wave thus would be 2cm x 8cm, when using epic bases, the wave would remain 2cm x 8cm.