Re:
Doesn't really matter who you use, it's how it's packed that counts. Get the sender to do a good job. When I send frames or bikes I use pipe lagging around frame tubes and bubble wrap in addition. I've had franes arrived damaged as theyve just been thrown in a box alongside wheels, so cassette, qrs etc bang around, alongside other bits not secured. If it can't move, and it's protected it should arrive as intended.
Get the seller to take pics of packaging prior to sending, just in case it is handled badly buy whichever carrier you choose. If you need to claim, evidence helps. Speaking of which, insure it to the full value.