MD correlates in my experience better to audibility and is surprisingly* a bit tad lower on the LS50:
* Surprisingly as the LS50 has a smaller driver and is a coaxial design, it seems its midwoofer motor is a better design though.
Also horizontal and vertical directivities of LS50 are quite supperior:
so it responds to EQ better.
Both great loudspeakers in their price range so like always there is no clear general or objective "winner", it most depends on the usage, for example for nearfield and desktop monitoring I personally prefer coaxial designs like the LS50 due to relatively large change of vertical listening angle when changing posture and due to the reflections of the desktop surface.