just a few points
Eddie Vedder does play guitar, especially on the more recent stuff, I've seen em live twice and he plays on around half the tracks :)
I forgot to Mention Pete Townshend, dont ask me why, but I would say HE is the greatest songwriter of all time
Led zep next, most of the songs were lyrics by plant, music by jimmy page, although john paul jones and john bonham co wrote on a few tracks, black dog is one that springs to mind
I personally would disagree with young and dylan being untouchable, I love neil young, but with 38 albums to his name, he's written some junk as well as some genius stuff
I dont rate the beatles much at all, but the sheer amount of people who love them, means they've got to have done SOMETHING right
and yeah Cale did write some of clapton's more popular tunes, but think about layla, have you ever loved a woman, tears in heaven, pilgrim, wonderful tonight, the list goes on, he's written some amazing material of his own too.
Peter Green is another fantastic songwriter, as is andy fraser, ok he's a bassist, but I had to slip him in
Honestly, it's all down to personal perference here, a song that speaks to one person, another person may hate, it's soo subjective, although I love talks like this, I love hearing about people I've never heard of, so I can check em out!
guns dont kill people, people kill people, and monkeys do too (if they've got a gun)