I use a soft-side padded ski bag and have had no problems with airline handling. The drawback with a hard-sided case is, when you arrive and try to put this rigid bulky container in a rental car or SUV it will always be in the way; if it fits at all. A padded ski bag can fit in a vehicle, or the skis can be removed and the bag can just be folded up allowing you to use a ski rack. Mine is built for 2-pairs and has tiedowns, so I usually pack extra clothing to further pad the skis. Also has rollers for easy dragging, sholder sling and suitcase handle.
A hard-side case protects skis from bending and impact on the ends, but still transfers shock from dropping, which seems to be the most common shipping issue. Use soft-side and extra padding.