Hehe Yoshimitsu kamekaze attack is nice, I killed my brother with two harakiri
Personally I like a lot Cervantes, he's good at any range and can do well in most situations.
I don't do well with Ivy because her moves requirer you to combo them, but I agree she's the most powerful when you know how to play her.
I love the fact they splitted Siegfried and Nightmare into 2 different characters, makes it more fun to play