Most of the folks on this site will advise you not to buy a toilet online. Too high a risk of breakage during shipping. There are anecdotes of people buying an online toilet, that seems OK, and installing it only to find it does have a small crack that they didn't see, and which causes a leak. Not fun to then take a used toilet out of the house and make a warranty claim.
Elongated bowls are highly preferred so if possible would be best to use. You could make a mockup out of cardboard to see how it will fit in the room.