I think that the character I find the most fun to play with is... Kano...of course, no surprise here.
Everybody that had read any of my posts about the character knows that I absolutely adore how the devs have designed the character for this game, even taking on account all his flaws.
In addition, bearing in mind that I'm a grappler/brawler type of player, this character seems like something designed by/for me. Can't explain how much I enjoy doing lumbar checks in the neutral and trying to mix up people with his tick throws while listening some HxC Punk in my headshet.
Another honorable mention is Cassie, my secondary (I only use characters that I find fun to play) . I love her neutral game and specially her gunplay. In fact I decided to have her as secondary the first time I got bodied by a player mixing up all her gun attacks (Knee cappin, Dual Wielding, Air Bullet Barrage and I believe that even a few Flipping Outs!!!), and I'm not talking about zoning, but about incorporating them in combos and neutral play. I was fascinated by this playstyle so I tried to imitate it.
Out of my mains, I'd like to mention Jax, as he can be played as another Grappler/Brawler character, something that I enjoy so much: Keep it simple, don't care about combos, don't care about zoning, only grabs, short strings, more grabs and footsies, hell yeah!!