Dependents on my mood, but now days I mostly listen to Tchaikovsky, Wagner, Beethoven and many other composers of romantic period. Sometimes I will pop in a movie soundtrack, or electronic music ( trance, dnb, dubstep, psychodelic etc ). Can't listen to rock music cause my favorite bands indulge me too much in to their music ( alto with my favorite symphonic music I do sometimes stop programming and listen ).
But going back to symphonic music - I love it especially in the early stages when programming and designing because it take me into many places, and inspire me on different levels which then translates in to really good ideas.
PS( Romantic doesn't mean roses, moon, dinner with candles etc. It'a common misconception but true name for that is sentimentalism, and it's bs. Romantic means emotionally polarized. ;) )