One of the best bets in the Who-Will-Be-the-Next-Pat-Benatar Sweepstakes is this versatile vocalist from upstate New York. Once an aspiring actress, she was discovered by poet-singer Leonard Cohen, who hired her in 1977 to sing backup. Now 24, she is strong and fresh in her debut LP of nine songs. Half her tunes seem geared for a cabaret, and the rest are rock-palace specials. She's dandy, though, delivering sizzlers Gloria (not to be confused with Van Morrison's G-L-O-R-l-A), Living a Lie and Please Stay, Go Away. And she's equally facile with more subtle romantic songs like If You Loved Me. Most impressive is Branigan's I Wish I Could Be Alone, a tender two-timing tune.