What's the best dining table for a square-shaped living room?

I just recently moved into a condo/apartment. The living room's kinda small and it's square-shaped (the living room doubles as a dining area and the kitchen). I'm planning to get a dining table but I don't know what kind of shape to get. I wanted something that wouldn't make the room look crowded. Also maybe an advice on how to position it would be helpful. Do I place it at the center or have it against the wall. I want the whole area to look inviting and with decor, and not just about functionality.