Well, it should be plant cell, the cell wall is turgid thus it gives the plant cell a regular shape. Animal cell doesn't have a cell wall, only a cell membrane while plant cell has both cell wall and cell membrane, so it is irregular in shape. Look at a muscle cell and a red blood cell, they have different shapes.
Animal Cells are round. Plant Cells are kind squarish/rectangleish. & Plants Cells have two more parts then Animal Cells do.
Plant cells have a regular shape, because they have a cell wall. Animal cells however, do not, so their shape is not regular
Considering niether plants nor animals are made up of a single cell type I wouldnt say either of them have a regular shape
polygonal, columnar, sqaumous... there is quite a lot of variation in cell shape depending on what its function is
Most of them have similar shapes to that. Round, oval ect..
animal cells are not all round