Hey Bonhe! I was just asking about you! We missed you!
In this case, I think it depends on the styling of the tree. Side A has a twisting motion to it that might work better with a more informal style. Side B is more static and might work better for a formal style.
All things equal, I prefer Side A because the roots seem to be grasping the soil better. Side B the roots seem to be going straight down. Side B is a little boring to me.