Offenbach, when I want to boogie.

Strauss when I want an uplifting distraction.

Shostakovich for creepy and delightfully screechy evening music.

Mussorgsky for chill and ponderous weekend morning music.

Brahms when I want to sit and sway.

I don't have a specific time or mood other than being in the mood to listen to that particular composer. Anyways, my choices are Tchaikovsky, Prokofiev, Sibelius and Beethoven. I also find the director makes a huge difference in my enjoyment, just any version won't do.

I skip the mental process of 'my mood is X so let's listen to composer Y'. How I feel simply makes me feel like playing some Y (or some specific piece, or some type of music since composers often have pieces with different moods, and the type of piece and instruments plays a big role).