What should I cite?

According to AGLC (rule 2.3.1), when a case has more than one citation, you should use the most authoritative version. That is:

• A reported version of a case should be cited in preference to an unreported version.

• Cite from an authorised report series if available: (ie. USE: CLR, FCR, ACTLR, NSWLR, NTLR, Qd R, SASR, Tas R, VR, WAR)

• If the case is not available in an authorised report, use a generalist unauthorised report series (eg. Australian Law Reports) over a subject specific unauthorised series (eg. Australian Torts Reports)

• If the case is unreported use the medium neutral citation (if assigned by the court)

N.B. Appendix C of Catriona Cook et. al., Laying Down the Law (8th ed. 2012) provides a comprehensive list of many law report series and indicates which are the authorised reports of each jurisdiction.

This practice is also expected by the courts. For example, the High Court of Australia states in its Practice Direction No.1 of 2000 - Written Submissions and Authorities that:

The written submission of the appellant shall

...contain... a citation of the authorised report of the reasons for judgment of both the primary and the intermediate court in the case (or, if there is no authorised report of the decision, the citation of any other report of that decision, and in the absence of any report, the internet citation)