Oh man, this will be a tircky one, Trilogy is the final edition of MK3 but it was released on PS1 and N64
MK1: Was really cool back then, I always loved the "Test Your Might" mode (simpler on Arcade than it is on Genesis), and the simple pit fatality. Other than that it doesn't hold up well
MK2: This one was awesome back then and it's always awesome, a huge update in everything over the first, truly deserves to be on every gen of consoles from the NES to the PS3
MK3/UMK3/MKT: The earliest version made me a little upset, no Scorpion, no masks, and Sub-Zero's uniform looks ugly, I knew back then he was the younger brother in this game, but in MK2 I though the older Sub-Zero was playable, and how we had Sub-Zero in UMK3 and MKT doing the ice on the ground move.
UMK3 on the arcade is kinda sad, no Rain, no Noob Saibot, I'm glad the character roster for consoles was different
I love how both Sub-Zeroes were in UMK3 & MKT, as well as that was being before the days of Quan Chi, and Noob Saibot was a being from a different clan, not the older resurrected Sub-Zero