For your abs
For your abs, the two are close. Ab wheel rollout rates slightly higher: more stretch.
Hanging leg raise is easier on the joints.
Both are good choices, and they train the abs differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed. (Fonseca et al., 2014; Costa et al., 2021)
The research score comes from these, scored by hand from the studies. Lifter scores appear once an exercise has 10 ratings. How scores work
Ab Wheel Rollout. Hard work for the abs in a stretched position, but difficult to progress and tough on the lower back if form slips.
Hanging Leg Raise. Curling the pelvis up trains the abs hard, but grip and hip flexors often end the set first.
For climbing, hanging leg raise rates well ahead on our research criteria: more carry-over to climbing.
For your abs, the two are close. Ab wheel rollout rates slightly higher: more stretch. Hanging leg raise is easier on the joints. Both are good choices, and they train the abs differently. Using both across your week covers more of the muscle than either alone: in studies, varied exercises grew parts of a muscle that one exercise missed.
About the same: both take some practice.
Ab wheel rollout needs no equipment, so you can do it anywhere. Hanging leg raise needs a pull-up bar, so a home gym covers it.
Hanging leg raise: it rates Strong for joint and recovery cost in our research rubric, against Good for ab wheel rollout.