Keep pelvis component-space and follow along all of the actor's vertical ground movement. Use when you have really smooth ground geometry, or if you have moving platforms.
WorldSpace
Hold pelvis world-space and ignore the actor's vertical ground movement. Let springs interpolate the difference.
SuddenMotionOnly
Keep pelvis component-space, but hold world-space transform when the actor does sudden changes (i.e. a big step), and let springs interpolate the difference. Does not work on moving platforms.