Compiling an “essential” double-album set for the satin-voiced Isley Brothers is difficult, given the musical range of their decades-long career. But this one’s the best. It shows the group skillfully changing with the times and their clear influence on musical history: rousing doo wop-soul hybrids (1959’s “Shout, Pts. 1 & 2"), their 1966-’68 stretch at Motown (the stomping version of “This Old Heart of Mine”), psych-funk (the 1969 smash “It’s Your Thang”), singer/songwriter fare (1974’s “Summer Breeze”), silky ’70s tone-setters (“That Lady, Pts. 1 &2”) and late-night candle-burners (1995’s “Down Low” with Jay Z).