So flat straight forward you'd say? Instead of angled like a triangle.
Unfortunately, there is no straight forward answer to this question, because the answer is based largely on your circumstances and preferences such as your room, ears, brain, etc. You also may not even know what you like simply because of lack of a lot of experience which is totally fine. For instance, maybe you want a very wide sound stage, maybe you like very narrow, etc. These are things that, at least in my own experience, you learn over time through experimentation.
To answer this question - I recommend experimenting with placement, toeing the speakers in, tilting the speakers back and forward, setting the tweeter height (raising or lowering the speakers), etc. until you find what sounds best to you.