Pager Team has three key considerations that differentiate it from the existing competition. Those are cost, configuration, and consistency.
VictorOps, Pager Duty, and Ops Genie all charge monthly by user. The more people on your rotation, in some cases even as mere observers, the more you pay. Rather than charging by the user, Pager Team charges by the incident, since that's where the costs are. I have two plans: a pay-as-you-go plan that charges $1/mo per rotation plus $1/incident, or a flat rate plan at $200/mo per rotation which provides unlimited incidents.
The configuration of all three incumbents is complex. You can make them do just about anything! It's wonderful, in the same way JIRA is wonderful. However, because you can do just about anything, configuring them is actually so complicated that it's easy to get wrong.
Consistency has two really important facets. Most important for the business is the consistency of response time. Regardless of the individual currently on-call, when an incident comes in, you want to see the same prompt response. Every Pager Team user has the same notification path which they can't change, so you know what to expect regardless of who is on-call.
The second part of consistency is for the members of the rotation. Everyone has a life outside of work and they need to be able to plan around their on-call schedule in a consistent, predictable manner.