Love the round one so much more.

With the windows bumped out like that, I think round would look best. If you share measurements of the space, I bet someone knowledgeable could suggest the appropriate size of table.

Do you have another formal dining area?

If so, then the first image (round table and white chairs) looks best, as it mimics the roundness of the bay windows and creates a casual cozy-kitchen feeling. The white chairs expand the kitchen by carrying the color through to the end of the room. If you choose a dark table, then add white seat cushions. An all dark wood table & chairs will chop-up the space into sections. Use white seat cushions to bounce the eye to the white used adjoining room. This will unite both areas.

If this is a great room with the dining table in the kitchen as in the case with many new builds, then keep the bigger table, as it fits in the space. Add lightness to the dining area by adding white chair cushions. See this transitional model home great room that shows a black table in a white kitchen. Link: https://tours.stevenjamescollins.com/public/vtour/display/209715

Round!

Round and no bistro chairs. Your space is not suited to that look. The fretwork chairs are great.

Definitely a round table in a lighter color. Here is mine next to the kitchen. A rectangular table in your area looks much too harsh and angular. If you can find one where you can insert leaves in the middle to expand the size all the better. I like the chairs in the first picture best, not the bistro.