Counting the tiles...there is no room for table/chairs.

Invest in a new countertop which allows you to add 3, possibly 4 (if not too wide) bar height stools.

Remove the rug, tape out the size of your buffet. Then tape out the size of the table with enough room to pull a chair out to sit down in. I think there is not enough room for table, chairs, buffet in this space. Perhaps a small round tulip table with two chairs? Or no buffet and an oval tulip table with four chairs. Still tight. Do you own? Would you consider removing the top overhang counter and cutting the wall down to the lower counter height? Would give you a bit more space in here for table.

What do you want to store in the sideboard and could you place the sideboard elsewhere in your home?

This is a rental and i cant adjust the architecture.

I need to store art aupplies in the buffet - it is extra skinny - 12” wide. A 29’x47” table could work or 36-38” round but i have two kids and an aspiring artist that needs to use the space.

Total floor space minus the island overhang is about 6’x8’

Is the aspiring artist an adult? Are they using the table surface to make art or are they using some other surface in this space or elsewhere? If art is to be made on the table, then I'd go rectangular for sure. Kids don't need to pull out chairs as far, so that bodes well for cramming this all in here.