I'm all over the map, but love stuff with an edge:
Heavy Metal - mostly '80s thrash along the lines of Destruction, Celtic Frost, Testament, King Diamond etc. Have hundreds of CDs from all genres of metal, but the 80's thrashers remain my favorites.
Space Rock - Hawkwind, Eloy, DarXtar, Pressurehed, Nik Turner, Farflung etc. Seriously spaced-out, hard-driving music heavy on atmosphere.
Dub Reggae - old stuff along the lines of King Tubby, Scientist, U.Roy, Lee Perry ... and the "house bands" of the more famous producers: Upsetters, Aggrovators, Roots Radics.
No Marley, but rather heavy washes of wacked-out, dubbed up dread!
70's hard rock and prog - Mountain, Rainbow, Uriah Heep, Frank Marino/Mahogany Rush, Sir Lord Baltimore, UFO ... and for some of the more proggy stuff in this genre: Nektar, Captain Beyond, Magma.
70's Japanese hard rock/blues rock (I once heard the genre called "Japfro") - Far East Family Band, Flied Egg, Flower Travellin' Band, Blues Creation, Strawberry Path etc.