Tremor (mostly Aftershock and Crystalline)
Sub-Zero (mostly Grandmaster and Unbreakable)
Cassie Cage (mostly Brawler and Hollywood)
D'vorah (mostly Venomous and Swarm Queen)
With the recent patch I started to play more Crystalline, after my go to variation (Aftershock) took a big hit with the nerfs. I play Metallic here and there too but mostly just because of the awesome look of the Lava skin (sadly it's now his worst variation).
Sub-Zero was my first main since I started to play the game and I am glad that Grandmaster didn't change "drastically" since launch. Although I liked the idea of Unbreakable more so I started to play him when the game was released, just to find out that Grandmaster is a better version of Unbreakable. I still like to use Unbreakable. Cryomancer I do play sometimes too, but only when I feel like it.
When I started to learn Cassie I always liked the Brawler variation. Ending Combos with the takedown punch looks cool and the brutality after a big combo feels so satisfiying. I picked up Hollywood later after Brawler got the buffs so I guess I was lucky to learn Brawler before. Still haven't learnt Spec Ops.
I really liked D'vorah in the Story mode and Venomous with the additional venom damage sounded interesting to me. When I figured she was really easy to learn I sticked with her. After some time I tried out Swarm Queen. Still need to learn her cancels properly, but when I land them it feels really great. The pressure game with her is sick. Have not tried out Brood Mother yet.
Side Notes: Started learning Kotal Kahn 3 days ago and oh boy did I miss out on this one. Son God feels most comfortable for me right now. I love the command grab and his godlike pokes. ON YOUR KNEES ALL DAY PIZZA BOYZ.
Following characters I do not main but still play: Jason, Erron Black, Scorpion, Ermac, Mileena, Triborg