If all you want are statistics then use either SNMP to query interface statistics and/or Netflow to export flow data.
Logging potentially will give you a record for every single TCP connection of UDP flow. Those are records more so than statistics and seldom used for real time analysis.
Packet capture is generally used for ad hoc troubleshooting. Packet tracer is similarly used for ad hoc analysis of a given known connection or flow.
All of the above are described in the ASA Configuration Guides.
