is there a perfect architectural shape

[Gustav]

most find instances of symmetry aesthetically pleasing tho......Only a bad architect relies on symmetry.....

 

[Billy T]

Yes, the rectangle.

Yes but only if the sides are in the ratio given by the irrational number that begins: 1.618034....

 

[R1D2]

The X shape is used in construction as "X bracing" , often seen on the outside of tube type buildings, but in these cases, the X has a top and a bottom which is normally a floor or spandrel beam.
This is what makes the X stable, it is composed of 4 triangles. The X by itself is unstable.

Yes someone is starting to get my point. |X| <-rotate it so the lines | are laying down _ it is strong.

 

[ccdan]

No, there isn't... costs aside, it's matter of taste (which is subjective) and/or practicality...