Which Delivery Services is better for you?
There are so many different shipping options to choose from, it’s difficult to make apples to comparison without locking down some of the basic parameters.
In my experience, I have had some Priority Mail packages delivered within a single day and I have seen delivery times as long as 1.5 weeks. While the latter tends to be an anomaly, overall the delivery speed is somewhat random.
If you decide to use USPS as your primary shipping carrier, the cheapest way to go is to use a service like ExtraShip.com.