I realise this may not be seem to be the most original thread but I wondered if posters would be interested in stating their favourite pieces and then what they consider to be the most neglected 'masterpieces' - if you can relate to the former the latter may be an incentive for discovery.
My own favourites have always included Mahler 9, Rachmaninov symphony 2, Tchaikovsky 6 and Strauss 4 last songs.
Anyone who can relate to those choices I would implore to listen to MAHLER 10 (in particular the final adagio movement as performed by Rattle and BPO - my favourite single most heart wrenching piece that I know), Arnold symphony 9 and Paul McCartney Liverpool Oratorio.
I would of course wish to mention many other pieces but brevity would help to keep suggestions flowing. I'm never inclined to listen to other peoples suggestions unless I can relate to their own favourites.