The honest version of "does it integrate with my software." These are the systems this industry actually runs on, and what each one means for a build.
AppFolioProperty management platform
The system of record in a large share of mid-size shops — ledgers, leases, work orders, owner statements and tenant portal. It has an API, though what is exposed is narrower than what the interface shows, so it is worth confirming reach before scoping anything that writes back.
BuildiumProperty management platform
Common in smaller portfolios. Similar shape, generally friendlier to integrate, less depth in accounting for commercial work.
YardiProperty management platform
The enterprise end, and the one most likely to involve a formal integration process rather than a straightforward connection. Worth establishing early what your specific deployment allows.
Rent ManagerProperty management platform
Strong in mixed portfolios and self storage, with a more open integration story than most of its neighbors.
Maintenance coordinationWork orders and dispatch
Either a module of the platform or a separate service. The recurring cost here is not dispatch, it is the three-way communication between tenant, vendor and owner about when somebody is coming.
Tenant screeningApplications
Credit, criminal and eviction history through a screening provider. The regulated part of the application process, and the part where the decision rules need to be written down and applied identically every time.
Vendor complianceInsurance and licensing
Certificates of insurance and licenses for every contractor who touches a property, usually tracked in a spreadsheet, and a genuine liability when one lapses unnoticed.
QuickBooksAccounting
Often running alongside the platform for the management company's own books, as distinct from the trust accounting for owners.
Phone and textTenant communication
Where most of the actual work arrives. After-hours calls, maintenance texts, and the same six questions asked continuously.