Round tables are an important aesthetic option, with some clear advantages. They are more welcoming, versatile, social and less annoying for diners: the legs are less uncomfortable and because there are no corners, we can avoid painful encounters. However, they require a very special space and are not suitable for crowded parties.
One of the first things you will have to ask yourself is where you will be placing your dining table. A round table curiously seems to draw all elements that surround it towards it, thereby anchoring itself (and the chairs) visually more than a rectangular table would. It also takes up less space.