With the help of his protégé, Elton John, Leon Russell is enjoying an acclaim that he hasn’t felt since the ‘70s when he made the transition from top-ranked session player — he recorded and toured with Jerry Lee Lewis, B.B. King, Eric Clapton, George Harrison and Bob Dylan, among the many — to a solo artist of his own renown. This “Best Of” collection is a small sampling of his fine work, but it’s a worthy introduction. His soulful vocals come from a place of genuine respect and love for music that’s half-pitched between country and blues. His 2010 collaboration with Elton John on “If It Wasn’t for Bad” represents his current renaissance while “Delta Lady,” “A Song for You,” and “Tight Rope” represent his most visible work from the 1970s. His funky arrangement of Bob Dylan’s “A Hard Rain’s A-Gonna Fall” is as daring as his New Orleans-influenced take on Tim Hardin’s “If I Were a Carpenter.” The full-band blast of the Rolling Stones’ “Jumpin’ Jack Flash” weaved into the old R&B tune, “Young Blood” from the 1971 concert for Bangladesh, sounds just as fresh forty years on.