I always use USPS whenever possible. Many times the estimated arrival date is correct, sometimes my box will arrive a day or 2 late, rarer yet is when it arrives a day early. lol There is no guarantee on their priority mail service, but I've found it to be quite acceptable over all. I've never had a package get lost or anything like that so far, though some of our members have from time to time. That can happen with any delivery service though.