I’m sure you will get many varied responses, but I would suggest these five for starters;
Symphonic
Mahler – Symphony 5, first movement – New Philharmonic / Barbirolli on EMI – heroic, exciting, and wonderfully played and recorded
Opera
Wagner – Siegfried, Act 3, scene 3 – the ecstatic extended duet between Siegfried and Brünnhilde – why not try Solti’s famous recording?
Philip Glass – Akhnaten – beautiful & shimmering waves of music; alternatively, Boulez's pli selon pli
String Quartet
Any of the Emerson Quartet’s recordings of Beethoven’s late string quartets; alternatively, the Smetana Quartet’s recording of Janacek’s second quartet
Piano
Whatever you like, but why not Tatiana Nikolayeva’s recording of Shostakovich’s 24 preludes and fugues, on Hyperion?