Brian McKnight's passionate-but-tender voice is a perfect vehicle to showcase his gift for writing sleek and sultry, gospel-soaked R&B ballad hits such as “One Last Cry,” but dig through his album tracks and you discover a diverse artist with far-reaching influences. “Sweeter” is exactly what the title suggests, a folky, acoustic love song, while “Forever” is slick, chart-smashing pop at its best.