Any of them will be fine as long as the cymbal has plenty of padding around the edges. I usually make at least an inch or two of extra padding between the edge and the box side. I think the concern with certain shippers is with heavier yet fragile items. Ups lady once told me that she was putting it on a conveyor belt and which drops it onto a loading bay about ten feet down. Ouch.
Something to keep in mind - ALL of the private carriers use the USPS to one extent or the other.
My sister's been with the post office for about 30 years now and she always sees those guys dropping packages off, when she goes to the big routing station in Seattle.
I use Fedex and they have been good...I have a buddy who uses USPS almost all the time. His theory is he gets less damaged packages because he says Postal workers are older, and can't throw the boxes as far.....lol