My favorite Morrissey single is "I Have Forgiven Jesus", bolstered by the rendition of "No One Can Hold A Candle To You". This is especially my feeling because I loved Morrissey's performance of "I Have Forgiven Jesus" on the Craig Kilborn show.
Adding to the excitement was that Morrissey had been AWOL for years before the triumphant return. My emotions at the time were almost too much for me to handle.
Runners-up: "Everyday Is Like Sunday" and "Boxers". But Morrissey's best songs have generally not been singles, so......
(Morrissey's best solo song is "Life Is A Pigsty", of course.)