As Mike says, one can use the OpenMRS Reporting module within Bahmni, and this would generally work fine. (Though, you’d need to add a way to run them to the UI.)
If Bahmni Reports provide most of the functionality you need, I’d go with them.
This thread gives a good example of how a hospital that uses Bahmni Reports also leveraged the Reporting Module for a use case it didn’t support: Sending email with summary of daily admissions