Favorite conductors for composers

early music:  1400's-1700's (even including a recent recording for Beethoven's symphonies 1-5) Jordi Savall

Bach choral works: (Passions, cantatas)  Jos van Veldhoven

Chopin piano pieces: (not conductor, but performer)  Claudio Arrau

Bach piano pieces: (not conductor, but performer)  Glenn Gould

most violin compositions: (not conductor, but performer)  Itzhak Perlman

Try some Gustavo Dudamel. Anything.

Bernard Haitink for the Shostakovich symphonies.

Daniel Barenboim and the CSO for the Bruckner symphonies.

Colin Davis and the BSO for the Sibelius symphonies. 

Another vote for Karajan's Beethoven. His 1963 cycle is a masterpiece.
Bruno Walter and George Szell also for Beethoven.
Mahler...Bernstein, Walter, Furtwängler, Boulez, Claudio Abbado.
Bruckner...Furtwängler, Giulini.
Brahms...Bruno Walter, Toscanini, Carlo Maria Giulini.
Tchaikovsky...Bernstein.
Sibelius...Karajan, Eugene Ormandy.
Schubert...Edward Gardiner, Charles Munch, Claudio Abbado.

Vladimir Ashskenazy for Shostakovich, Tchaikovsky, Rachmaninoff.

Bernard Haitink, one of the best modern conductors.

It's tough to go wrong with Leonard Bernstein with anything. Feel a hankering for those Russian ultra-romantics Tchaikovsky, Rachmaninoff and Rimsky-Korsakov?  He's your man.  Bruno Walter truly unearths the souls of Beethoven, Brahms and Gustav Mahler. I think Bruno Walter actually knew Gustav. Walter's records have surprisingly good fidelity, too. Neville Marriner finds suavity, energy & grace with Mozart and Haydn.  He makes the tunes those guys wrote really sing. Try Gustav Leonhardt for J.S. Bach. No fuss. No muss. Get up and dance. Benjamin Britten was not only a superb composer, he could really swing a stick. It doesn't hurt that London-Decca gave Britten's efforts some of the best sound quality you'll ever hear.

Karajan for Beethoven, the 6th, 7th, excellent. He takes great care for the 'less famous' ones as much as for the 5th, and of course the 9th. But honestly, half the fun of listening to classical is comparing how different conductors interpret various composers. 

Herbert Von Karajan for Beethoven. I have about 5 versions of the Pastorale symphony, and for me, he brings it to life more than the others, even though the others are technically excellent.

Rudolph Kempe for Richard Strauss!

Bernstein is my god.