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.
The space that your dining table inhabits should have a natural impact on the chairs you choose. For example, if you have a tall table in a contemporary kitchen area, you might prefer some tall bar stools, to give a breakfast bar look. Whereas, if your table is in an open-plan room, you'll want chairs that align with your sofa choice and other decorative touches!