They are none.

Oracle Hospitality PMS is a good tool for large hotels.

I have worked at several hotels and two of them have utilized the Opera PMS program system. The system is difficult to functionally (and correctly) use in the midst of actual front desk/guest service work. It does not seem like the creators of the software gave any consideration to the reality of hospitality work nor the actual experience of a front desk agent. Primarily, the software seems to require too much attention to minute details (such as requiring exact alignment when moving guest rooms on the room map) and not enough attention to other necessary details (it fails to flag incorrect credit card procedures relating to rate code). There is also an obnoxious amount of clicking required sometimes in response to the software presenting second guess like questions (such as asking if you're sure you want to check in someone even after you press the checkin button). From a Front Desk agent standpoint, the software is barely functional and its ridiculous intricacies waste time and actually detracts from quality guest service.

Opera is a well maintained and state of the art property management system, especially for hotel franchise operations seeking connectivity to their central reservation system. An intuitive design shortens training time and they also have a training system that newbies can be logged into without damaging solid data. Reporting and segmentation of the reservations allows for deep dives into the nature and location of your guests. All nd all for some franchise it is a requirement for others perhaps it should be.

Great for financial reporting, cooperate with 3rd party software