I would suggest taping out the 3 different sizes/shapes and consider the space required when chairs have to be pulled out. If you want to add a console or cabinet along the back wall, a rectangle would probably fit better. Not sure if that is a window on the left - ie: can table extend over onto the left a bit - if not, the round (and without a console). When you do have people over, is seating for 6 or 8 preferred. Do you have a chandelier as table has to be centered under it - so length of a rectangle table will have to work. Style wise: which shape do you prefer on a daily basis. I wouldn't worry about the other half of the room in regards to shape/size; need only consider living area in regards to style. You may also want to consider a table that has an extension so that it can be more intimate for your family and you'll have more room around the table on a daily basis.