Massive Attack reviled the very idea of “trip-hop,” but they were the ones who took breaks and samples away from hip-hop and set them sailing in inner space. With a member specializing in each genre of rap (Mushroom), dub (Daddy G) and post-punk art rock (3D) and guests as diverse as folkie Tracey Thorn, evil genius Tricky and reggae geezer Horace Andy, their big old melting pot was justly celebrated for the rich, deep, dark stuff below its surface. That accounts for just under half of this best-of. The rest charts Massive’s retreat into the narcotized margins as Mushroom departed and Daddy G was sidelined. 3D gets some diamonds (“Angel,” “Teardrop”) from his frosty version of the band, but his material is mostly abstruse and over-represented here and on the bonus disc.