The best listening position depends on the speaker setup and the room. In my opinion, it's not good enough to have a small "sweet spot." I prefer setups that offer a large area in the room where sound is good.
Study room acoustics. Study loudspeaker directivity. After that, you'll have more information to work with and will be able to know how to setup your room, including where the best places are to sit and listen.
I once read that to get the best out of the stereo speakers, the seat should be placed the same distance from the speakers, as they are from each other. The chairs and speakers should (ideally) form an equal-sized triangle. Again, the speakers and seat shouldn't be placed against the wall.