JCI does not recommend glass aquariums above 150 gallons. They are prone to splitting at the seams due to the pressure of the water. This can lead to problems such as small chronic leaks and/or dangerous structural damage.
Common shapes for glass tanks: Rectangle, bowfront, hexagon
Acrylic aquariums can range from 150% to 200% cost over glass tanks (due largely to importing costs from American manufacturers). But this additional cost comes with an absolute assurance of guaranteed quality, craftsmanship, flexibility (for moving) and structural fortification. There are many advantages to acrylic over glass. See “Benefits of Acrylic” for more on this.
Shapes are limited only by imagination. See “Shapes” for more on this.