The Best Buy at USPS is insurance for more than $200. Any amount over $200 forces a signature at the other end, and USPS will absolutely not deliver a parcel so insured w/o getting a signature. And it's quite inexpensive, starting at under $5.00 for $201 insurance.
That's only a few dollars more than paying for Delivery Confirmation --- which, despite its name, doesn't really assure you of much. (Trust me, I've learned the hard way.)
Delivery Confirmation mostly provides a tracking number, so that the buyer can track the progress of the parcel online. Fine, but that's a sort of video game, in the grand scheme of things. Insurance for >$200 doesn't provide the buyer with a tracking number, but it does something far better: It forces USPS to make the parcel trackable internally, so that they can answer to their insurance company. You (the shipper) can walk into any USPS office, hand them the insurance number, and they can find the parcel on their internal tracking system.
That's a distillation of a lot of experience, some of it bitter, plus lengthy conversations with several local postmasters and a retired postal inspector who lives near me.