Worst: I don't really dislike any design to be honest but if I had to pick one that's the worst, it would be Sub-Zero. I don't like a bulky young Sub-Zero.
Best: Sektor, Nightwolf, Reptile.
Worst: Scorpion, Jax (Get rid of those metal arms!!!)
best- everyone but reptile
worst- reptile, when are they going to learn that the reptilian look should be kept under the mask, give that guy some skin and a normal look.
MK3 Sub-Zero and Reptile lizard was a HUGE disappointment for me.