Crane outrigger pads are built in different lengths, widths, thicknesses, and shapes to meet the requirements of load capacity. Large square crane outrigger pads have a large surface area, they are not as easy to move around on the job site as round outrigger pads, which usually can be rolled into position by one person but have less surface area.
With the exception of mobility and perhaps placement issues, there really isn't much to discuss when deciding shape. The square options are typically more common, but having an additional set of round outriggers will always come in handy. But past that, sometimes it just comes down to preference.

Crane outrigger pad is a sturdy pad or safety tool that helps distribute the weight of heavy machinery more evenly across a
surface by creating a larger surface area for the machine’s outriggers to rest upon. This helps not only stabilize the equipment but helps ensure safety and protects the machinery, especially on softer, less ideal terrain. Crane outrigger Pads are often used with any machine that uses outrigger arms, down-jacks, or stabilizers such as Cranes, R.V.s, Boom Trucks, and other types of lifts.