I have been playing nothing but exclusively Jason since literally the Sunday of EVO, lol. He's pretty much my main and I've never enjoyed MKX more than I do now. He's really good and underrated. There's only three match-ups that are hell for him, but they're just 3-7s and you can win with the right reads.
Jason is my secondary character. I love, love, love playing as him. NRS did a wonderful job with his design, especially in Relentless. The sounds when you break their back, neck, throw them, etc., all match his character.
Feel free to add me to any Jason discussions you may have. I'm sure I'm not as well versed as you other folks are, so I'd love to learn more if possible.