Goku going SSJ3 or getting brutally beaten is always a good scream. Goku's voices pitch dramatically increases with the impact of Broly's blows, for instance; you can almost feel the ham-sized fist jammed into his stomach.
And yeah, the SSJ3 transformation's scream was sweet because it just kept on climbing. He didn't catch breath; it just got higher and higher until eventually it was so high-pitched that it blended into the sound fx of the transformation. Amazing.
Although personally my favorite screamer is Vegeta, all around.