AC/DC, Beethoven, Willie Nelson, Sinatra, Metallica, Blood Sweat and Tears, Beatles, Harry Chapin, Pink Floyd, James Brown, Mozart, Stevie Ray Vaughan, Tower of Power, Temptations, Black Sabbath, Puccini, Doobie Brothers, Prokofiev, Count Basie, Johnny Cash...and the list goes on.
I have no single favorite and have been known to stop Aerosmith in mid song and switch to Bach. It depends on my mood. In one week, I saw ZZ Top with Lynryd Skyryrd, James Brown and the Berlin Philharmonic live and was fine will them all.
I lean towards classic rock and old soul/funk, but sometimes folk or acoustic rock is what I need. Other times, big band or blues. Certain classical works are more effective at the gym for heart rate than some metal songs and when traveling back from Europe in the middle of the night, the best thing is putting on the headphones and cranking Pink Floyd while you contemplate hurling backwards in time in a tiny tube 33,000 feet over the ocean. Very trippy.
Nowadays, it is mostly just the odd song on the radio that I'll latch onto but would hardly call myself a fan of the artist. I do admire groups or singers for what they do, but not necessarily their output or genres.