The various Paul Simon-compilations that have been released over the years have been an unsatisfying bunch, leaving out some of his best and most succesful songs in favor of his own personal favorites, so none of those collections can be recommended unreservedly.
But "Greatest Hits: Shining Like A National Guitar" remedies that, and it is by far the best such collection ever released, selecting 19 songs from Paul Simon's studio recordings between 1972 and 1997, including all of his ten British chart singles.
Not quite as comprehensive as the double-disc "Paul Simon Anthology", "Shining Like A National Guitar" nevertheless gathers almost all of Simon's very best songs, including "Still Crazy After All These Years", "Graceland", "The Obvious Child", "Mother And Child Reunion", "Slip Slidin' Away", "50 Ways To Leave Your Lover", "Take Me To The Mardi Gras", "Me And Julio Down By The Schoolyard", and of course "You Can Call Me Al".
If you're looking for a place to start, this is it. And if you're looking for just one Paul Simon-collection, this might very well be it as well, especially if you already have the key Simon & Garfunkel-songs (which can be found on "The Paul Simon Anthology").
4½ stars - highly recommended.