According to VETASSESS, the assessing authority for Facilities Managers in Australia, before deciding on what occupation you should have yourself assessed with is to take a look at the job description based on ANZSCO against your own - review your previous and current job descriptions, which you can acquire from your previous and current employers. This way you have the best possible match to your job and the occupation to be assessed and get close to a positive assessment result.
Own it if you have it. Cheers!