Tom Waits - "Step Right Up", "The Piano Has Been Drinking (Not Me)", "Singapore", "Chocolate Jesus", "Goin' Out West". Waits started out with a very classical approach to writing low-down blues songs injected with just the right mix of humor and sadness. Once you get past his gruff persona and songwriting idiosyncracies, you see genius at work.
Leonard Cohen - "So Long, Marianne", "Hallelujah", "First We Take Manhattan", "Don't Go Home with Your Hardon". Cohen has dozens of odd love songs for every occasion, the amount of tail he must have gotten rivals that of any member of a hair metal band.
Nick Cave - "Where the Wild Roses Grow", "As I Sat Sadly by Her Side", "Fifteen Feet of Pure White Snow", "The Mercy Seat", "John Finns' Wife". Amazing since Cave's early efforts circa "From Her to Eternity" were juvenile stabs at melodrama. Most of his recent stuff remains melodramatic and indebted to folklore, but the style has been refined to a cool few artists could match.
Lou Reed - "Coney Island Baby", "Walk on the Wild Side", "Vicious", "Heroin". Whatever else you can say about Warhol, the man had taste. I don't think Lou Reed would have developed into such a mature and sardonic songwriter without his early years with the Velvets.
Roger Waters (of Pink Floyd) - "Wish You Were Here" has some of the best lyrics of all time, a breakthrough for Waters even after the DSOTM, "Mother", "What God Wants". I don't like his solo stuff as much, starting with "The Final Cut" the writing became a little too pretentious.
Michael Stipe (of R.E.M.) - "Driver 8", "Everybody Hurts", "Lotus", "Man on the Moon".
Cole Porter - "Love for Sale", "Don't Fence Me In", "I've Got You Under My Skin", "Let's Do It, Let's Fall in Love". Probably the most intelligent and interesting songwriter of all time.
Serge Gainsbourg - "Je t'aime... moi non plus", "L'hôtel particulier", "Requiem pour un con". At his best moments, Gainsbourg channels passion to create a playful moral bankruptcy that you can't help but stare at with awe.
Britt Daniels (of Spoon) - "The Beast and Dragon, Adored", "I Summon You (Cool)", "The Way We Get By", "Sister Jack". Daniels' songs are indie spirituals done right.
Cedric Bixler-Zavala (of At the Drive-In, The Mars Volta) - "Napoleon Solo", "One-Armed Scissor", the entirety of "Frances the Mute". A lot of people dismiss his work after joining the Mars Volta, calling it dense and incomprehensible. I don't disagree, except that I think emphatic nonsense has a beauty to it that's easy to love once you rid yourself of preconceptions.
Lennon/Mc Cartney (of The Silver Bugs, IIRC) - These songwriters are mandatory, so I won't even count them towards the 10 artist limit.
Honorable mentions go to Trent Reznor, PJ Harvey, Maxi Jazz, Bernie Taupin, Chris Rea, Maynard James Keenan, Marvin Gaye, Thom Yorke, Tom Petty and others.
