<<The UPS and Fedex are both much more inconvenient that the USPS and will make you wait longer than the USPS. They both have many fewer locations, and will make you wait longer. They are also less courteous, as a rule.>>
In Canada, the Postal Service was "privatized" to the extent that it was put into the hands of a Crown corporation. It's a for-profit business corporation but owned by the Canadian government. For sure it has many more branches than either Fedex or UPS, but OTOH, Fedex and UPS will pick up, whereas Canada Post will not.
As far as friendliness goes, I found all of them were more or less equally friendly and helpful. Waiting lines are much longer at Canada Post, but that's because they are by far the cheapest and therefore have many more customers.
The fastest and most reliable is Fedex, then comes UPS and then Canada Post. The most efficient and hard-working counter servers are from Fedex and UPS, some Canada Post employees are fully their equal, others are not.