i think round plates are more traditional and square plates are more modern. i think it really depnds on your own preference which you prefer. i dont have any square plates but i do like them i bet they fit in a square cabinet better. but they also seem somewhat bigger than round plates.
I prefer mainly round plates because square plates chip more easily at the corners. It's nice to have one size of plates (salad plates? ) square to provide a contrast.
The cons of using square plates relate to practicality. It's much easier to wash round plates by hand since you can easily wipe the edges in a circular motion. Also, square plates may chip easier since they have pointy corners. A positive of square plates is that they are unusual. This can help to make your meal enticing.
there really isnt a benefit to either, its all just personal likes and dislikes. i think square plates are cool and diffrent and if i found some id buy them!!
While round plates are much more traditional, you may find the square ones to be much more convenient. They will fit better in your cupboard space, stack easier, and just fit in any storage space easily. Square plates also have more modern look, and will spice up the dinning room just a little. I would recommend the square, personally.