Essential Beethoven

Beethoven: Piano Concertos Nos. 1 & 2
Beethoven: Piano Concertos Nos. 3 & 4
Beethoven: Piano Concerto No. 5; Mozart: Piano Sonatas Nos. 11 & 17
Why? These three imports are a bit hard to find (but available from third party sellers at Amazon) are remarkable and timeless (recorded in the fifties). All three garnered the coveted Penguin Rosette and are well worth seeking out.

Beethoven-Harnoncourt: 9 Symphonies : Why? Another hard to find import, Gramophone Record of the Year.

Beethoven: The Nine Symphonies : Why? These Solti/CSO recordings, recorded when the orchestra was at it's prime, are highly recommended.