S: Ermac, Jason, Sonya, Sub-Zero, Kitana, Takeda, Predator, Liu Kang, Smoke
A: Alien, Ferra/Torr, Kenshi, Scorpion, Mileena, Jacqui, Shinnok, Kano, Kotal, Reptile, Quan, Tremor
B: Jax, Cassie, Kung Lao, Kung Jin, Tanya, Bo Rai Cho, Leatherface, D'Vorah, Raiden, Goro, Sektor
B-: Cage, Erron Black
C: Cyrax, Cyber Sub-Zero
These are my initial reactions, A could be broken up into a plus and regular group, but I don't know the new game well enough yet though.
S: the best
A: great
B: good
B-: pretty good
C: pretty not good
Ok I'd change some things now and I'm ready to add an A+ to seperate the A group. Characters aren't ordered within a tier, any character in the same tier could theoretically be better than any other they share a tier with. I counted the Triborgs as different characters entirely, but if they were counted as the same, then CSZ and Cyrax being low tier wouldn't effect Sektor and Smoke which would make Erron Black the worst character in the game as a whole.
S: Ermac, Jason, Sonya, Sub-Zero, Kitana, Predator, Smoke
A+: Takeda, Mileena, Liu Kang, Tremor, Reptile, Kano, Quan
A: Shinnok, Ferra/Torr, Kenshi, Scorpion, Raiden, Jacqui, Kotal Kahn, Sektor, Tanya, Alien
B+: Cassie, Kung Lao, Kung Jin, Goro
B: Bo Rai Cho, Leatherface, D'Vorah, Cage
B-: Jax, Erron Black
C: Cyber Sub-Zero, Cyrax
S: the most dominant characters in the game, few losing matchups and many dominant ones
A+: a dick tip away from the top, has either slightly less winning or more losing than the S group
A: very good characters, not as overly dominant as the A+ and S, typically at least 1-3 very hard matchups
B+: good and solid characters, but unlike the A tier have several key exploitable weaknesses with some very hard matchups
B: very close to the B+ but have been abused by Paulo a bit more
B-: not bad characters per say, but have big weaknesses that hold them back, but are still useful for a few matchups
C: numerous and exploitable weaknesses that will hold them back, they are no true counter pick, they have some strengths that keep there from being a D tier, but these C tier characters don't really fulfill an archetype that isn't already filled by a better character.
I also still think it's funny that some things never change. Tremor, Quan, Raiden, and Reptile are still the most disturbingly underrated characters in the game.