Since you realize the limitations of both the room and the set-up of your equipment, I would also think that you have some ideas as to just how much of an improvement different speaker cables are going to make.
If you view putting together a system as three logical processes ... 1) choosing the speakers 2) choosing the equipment 3) choosing cables, accessories, and tweaking ... you are in process #3. I have found that process #3 enhances to a limited degree the speakers and the equipment and does not make up for huge deficiencies in the sound.
So given your room and speaker set-up situation, any differences you hear by changing speaker cables are most likely not going to be all that major or significant. You may perceive a difference and that perception may be important to you, but that would be about it.
Since you asked specifically about cables, I am not sure if you are looking at other things you might be able to do to tweak the sound. Cables would not be the first thing I would be tweaking. I would look at something like a graphic equalizer or a
BBE Sonic Maximizer . I have used a BBE in a basement listening space with success.
Rich