Dual plane, no question offers better low end torque. That is what they were designed for.
Single plane is a high rpm/top end type manifold. Poor low speed runner velocity.
Blanket statement that's mostly true.... but, not in all cases. Small block Holley Street Dominator was a single plane that I did a comparison against other dual plane intakes such as Weiand Action Plus and factory cast 4bbl intake and the SD cut the same 60 ft times. Some stock engines came with single plane intakes that created lots of low end. Like the older 318 single plane, not shy on punch whatsoever.