Generally, hubless sprockets are better for dead axle applications, as they transfer the torque from the sprocket to the wheel by bolts, with the assumption that there are bearings in the wheels for the axle. Since they are "dead-axle", the axles do not spin.
Sprockets with hubs are better for live axle applications, as they use the broached (either keyed or hex) shaft of the axle to transfer the torque. With live axles, the bearings must be in the robot chassis, as the entire axle spins.
