It depends on your room layout and how you plan to arrange your furniture. A round rug adds softness and flow to square or symmetrical spaces, making it ideal for small dining areas, foyers, or curved furniture groupings. A rectangular rug usually works better in long or narrow rooms like hallways or under sectionals where clean lines help define the space.
You can also explore other shapes based on your design needs - square rugs for balanced layouts offer a modern, structured look, while oval rugs for transitional spaces provide gentle curves without the full symmetry of a circle. The right rug shape depends on your space, furniture footprint, and design goals.