I've mentioned this Cup System over the last few years and it picked last year's winner. It's "Aspro's Melbourne Cup System", presumably soon to be posted by Racing & Sports:

Rule 1 - List any Cup acceptor placed in either the Caulfield Cup and Mackinnon Stakes (now irrelevant moved to finals day)
Verry Elleegant, Anthony Van Dyck, The Chosen One

Rule 2 - List any Cup acceptor placed 2nd, 3rd or 4th in the Moonee Valley Gold Cup
Miami Bound, Oceanex

Rule 3 - List any acceptor who was placed 1-2-3 in the Melbourne Cup at their last cup run
Vow And Declare, Prince Of Arran

Rule 4 - List the Lexus Stakes winner
Ashrun

Rule 5 - Delete any horse whose last run in the Melbourne Cup was an unplaced run.
Goodbye: The Chosen One

Rule 6 - Delete any horse who is aged 3yo or 7yo or older.
Goodbye: Prince Of Arran


So per this system, the winner comes from: Verry Elleegant, Anthony Van Dyck, Miamia Bound, Oceanex, Vow And Declare, and Ashrun.

There must be some doubt regarding Vow And Declare there, back-to-back winners are kinda rare...

Note also that it doesn't account for debuting foreign runners, which was considered a bit of a negative thing for a while, but is well and truly not as great an issue now. The only eligible debuting international this year though is Tiger Moth. Stratum Albium is out due to Rule 6. Both Master Of Reality - arguably, I guess - and Twilight Payment are omitted due to Rule 5.