sam - speacial in no sketch... he may have probelm fixing thing.. but it's ok.. his art are simple, (kinda) clean and drawing hands is not too hard for him
sai line is very suit for action or tense line for emotion of angry and extreme
faby can sketch and have line art very clean and bold...
his artstyle are ever changing (never do the color though) most of the time the art are like a skecth or foundation for drawing detail... but if he focused... he could use aspect of shape better than any of them