I never owned MKII I was just playing in the SNES of a friend. I voted DA, cause of the schock value, not only of Shao Kahn "Oh, he is still alive then? Oh, not..." and Liu Kang's death (finally), but also of the impovement of the graffics.
MKII is still great however.
UMK3 I don't like, but I have a secret love for MK3:
The psx intro for MK4, the so called comercial was awesome.
MKD had great story though the video per se is more imformative than great.
SM is a stupid game, and the video alone is contradicting established story, so though impressive, still stupid for me.
MKA was interesting the first time I saw, mostly cause I thought it was just a compilation game but I recalized there is a story behind it.