Check out the official site and wiki for the full list and other info.
I compiled a playlist according to this ABC list. Only three symphonies by Australian contemporary composers are missing on Spotify. For every symphony I tried to use my favourite recording. For Mahler, I chose Kubelik for No.1, Abbado and Lucerne Festival Orchestra for No.2, Bernstein and NYPO for No.3, Boulez for No.4 (because the Szell recording is not on Spotify for now), Barbirolli for No.5, Mitropoulos for No.6, Solti for No.8, Klemperer for The Song of the Earth, and Haitink for No.9. It would be great if you can share your oponions on the best performances of these symphonies.
Here's the Spotify playlist: ABC Classic FM's Classic 100 Symphony (451 tracks, total time: 2 days) Arranged from from No. 100 to No.1.