I also like the triangle boxes that all the carriers have. They seem to hold up but make sure the cue does move inside of the box.
On a similar note, when shipping in a tube of any kind, be sure to secure the caps on and pack the cue tightly. I saw two today that the pin was sticking through the cap. Too much travel inside. Add something extra.
Do not just slap some scotch tape or even clear packing tape to hold the caps either. That tape rips very easily and the caps fall off. Use duct tape or some other linen based tape.