Erron Black.
He was awesome. If every new character in MK was like him...

Liu Kang.
Impressive. Not radically different from before, but much more in line with his inpiration (Bruce Lee) and more gritty and flashy. One of the best X-Rays in the game. Though his Dualist variation could have been more interesting.

Shinnok.
Underwhelming. He seems to be Shang's demi-clone with rather incomplete / curt movesets. From the fallen elder god, not to mention character who was never properly realized before, I expected something much more interesting and grandiose.