At the time I enjoyed both. My uncle owned Street Fighter 2 for snes. My cousin rented Mortal Kombat for Genesis and we played the crap out of it.
Nostalgia wise I (like others) have more attachment to Mortal Kombat. The first and second games specifically.
I think the cheat menu of the Genesis version made the replay value very high. The controversy surrounding the title certainly helped.
Mortal Kombat 2 for the snes was pretty epic.
Trilogy for PlayStation was alright finally giving us the ability to play as boss characters without cheats or glitches.
After that Mortal Kombat kinda lost its way for a while.
Once they stopped using digitized people I lost interest.