Room Question

I’m making plans to finish part of my basement and move my system from the family room to the basement. The finished basement area will be in an L shape with one section being 15’ by 18’ and the L section being 12’ by 15'.

In the 15’ by 18’ section, there’s an off center 40” wide HVAC duct that runs the entire 18’ length. The 90” high ceiling in the 12’ by 15’ section is flat.

My question is… would it be smarter to use the 12’ by 15’ section for my system or take my chances with the off center HVAC duct?

Thanks