Assuming you’re talking about ideal from a sound quality perspective, you also need to specify a listening position.

Only the red locations have an implied stereo triangle with the pictured furniture. (north blue couch).

They are also similarly in the corners of the room - symmetry of placement is good for imaging.

Floorstanding speakers tend to play lower octaves, and any bass producing speaker in a corner will reinforce the low end by ~ +9db, due to the 3 boundaries the speaker is near. This will practically sound like extra bass, and it may mask other midrange detail as a result.

If your objective is causal listening in the entire space (for instance you enjoy listening while eating at the dining table), I would suggest the red location.

Overall, your listening space is full of compromises, and you’ll have to decide what you value more - sound quality, shared uses, aesthetics, etc.