MK reached perfection at MK3 for the SNES. After that with the new systems the combos and moves became too hard for a terribly uncoordinated person like myself. (That's why the last game I played was Diablo II, the easiest game on earth)
I guess my favourite move would be the Liu Kang bicycle kick (hold low kick for 5 seconds and release)
I always was good with that dude with the two hooks that ran thru opponents and they spun like crazy and there was some stupid 7 hit combo...I'm sure that made sense!
My favourite fatality was...I can't remember many but the Sub Zero one where he freezes them then breaks them over his head was pretty damn cool.
It's not the best. Up until 2 or maybe 3, it was okay. But after that, it just went downhill. The number palette swapped ninjas just got ridiculous. MK Trilogy (N64) was the worst for that. And the number of -alities was stupid. MK was never very good, it was just that the "OMG WOW BLUD!" factor was enough to keep it alive.