My main: Ferra/Torr, because they are cute and adorable together, and they give me positive feelings. Positive feelings are good for my health. Torr throws Ferra around, Ferra stabs Torr in the back, then they take walks in between rounds and she cuddles him if they win the match: looks like a healthy Outworld relationship.
Alternate: Liu Kang, because he is cool and all Bruce Lee-like. (I smiled when he showed the bouncy Jeet Kune Do feet in the story mode while fighting Raiden.) His movement speed is very quick and Dualist is a fun variation to play. Though, after the last patch, I completely moved on to Jason.
New alt: Jason Voorhees. I really like him as a character. The way he looks at the opponent in between rounds as if he's curious about them, then continues breaking their spine and choking them (non-Slasher) is very neat.
I barely knew the pre-patch Damned damage buff since I spent most of my time with his Unstoppable variation, so it's more-or-less whatever to me that it became a clutch buff. The old buff sounded really cool, though. After the last patch, I shifted my focus to Relentless.
(I have never watched any of the Friday The 13th films.)