I'm going to separate this by genre; I'm slightly obsessed with music.
For metal: I like Nightwish, too, and I'm quite fond of Judas Priest, Black Sabbath, Ghost, Disturbed, and Megadeth.
Mostly, I listen to punk; my favorite punk bands, in order, are Crass, Anti-Flag, Dead Kennedys, G.L.O.S.S., The Hex Dispensers, Minor Threat, the Ramones, The Sex Pistols, Social Distortion, Bikini Kill, Germs, MDC, No Problem, Limp Wrist, Circle Jerks, The Offspring, The Exploited, and Days N' Daze (which is a folk punk band that fits the attitude, but not the sound of every other band in that list).
I'm also really into goth rock; my favorites include Faith and the Muse, Siouxsie and the Banshees, London After Midnight, Bauhaus, NU:N, Rosetta Stone, and 45 Grave.
The Pretty Reckless, The White Stripes, and Royal Blood would be at the top of my list for modern rock bands; Joan Jett, AC/DC, and the Rolling Stones take it for classic rock.
For classical music, Beethoven rules everything, but Claude Debussy wrote several of my favorite classical pieces. Tchaikovsky, Prokofiev, Liszt, Mozart, Chopin, and Wagner are also good, and I like Ernesto Cortazar, who makes neo-classical stuff.
Electronic music goes to Daft Punk, Eisenfunk, MNDR, Knife Party, Junkie XL, Teminite, Valium Era, and Justice.
I haven't gotten into hip-hop or rap (yet) but I really like Salt N Pepa.
Finally, pop: I'm going with Michael Jackson, Madonna, Queen, and Vesala.
