The entire album “Bookends” by Simon & Garfunkel.
Perfect Circle - R.E.M.
Spain - Chick Corea
Gut Feeling - Hunters and Collectors (Australian Dopers will know who I’m talking about)
The Longing - Bela Fleck and the Flecktones
Further to Fly - Paul Simon
My favorites are:
Classic:
Clair da Lune-Debussy
Ninth Symphony-Beethoven
Piano Concerto #1–Tchaiskovsky
Tocatta in D–Bach
Brandenberg Concerto #5–Bach
Piano Concerto–Schoenberg (one of the hardest pieces ever composed to play)
Jazz/Swing/Tin Pan Alley era
Take the ‘A’ Train–Strayhorn/Ellington
Mack the Knife–as performed by Louis Armstrong
Rhapsody in Blue–Gershwin
Cocktails for Two–as performed by Spike Jones
Beautiful Dreamer–Cole Porter
Rock n roll/Neo-folk/Motown Soul era
Bo Diddley
I Can’t Help Falling in Love with You–Elvis
Rainy Day Women #12 and #35–Dylan
if I Were a Carpenter–Bobby Darin
Creeque Alley–Mommas and Pappas
I am the Walrus–Beatles
Get Back–Beatles
Respect–Aretha Franklin
The Big Payback–James Brown
Someday We’ll Be Together–by HDH, performed by the Supremes
The High-Concept pop era
Pinball Wizard–The Who
Won’t be Fooled Again–The Who
Fame–D. Bowie
Happy Xmas (War is Over)–John Lennon
End of part one.
Here is part two:
Disco–skip that
New Wave/Punk/Grunge–now known as Alternative
Loser–Beck
Jeremy–Pearl Jam
Black–Pearl Jam
Relax–Frankie Goes to Hollywood
Hip Hop era
The Message-Grandmaster Flash and the Furious Five
Gonna Make You Sweat–C&C Music factory
Don’t Believe the Hype–Public Enemy
911 is a Joke–Public Enemy
My Name Is…–Eminem
Peter Gunn–Art of Noise
Latino
Anything by Carlos Santana or Tito Puente
Reggae
Bad Boys–Inner Circle
A La La La La Long–Inner Circle
Redemption Songs–Bob Marley
Could You Be Loved–Marley
“Monolith” - Redd Kross
“So It Goes” - Nick Lowe
“Shelly My Love” - Nick Lowe
“From Here To Eternity” - The Only Ones
“12 Days Of Rain” - October Tide
“Baby Please Don’t Go” - Thin Lizzy
“Shoot Shoot” - UFO
“Lights Out” - UFO
“Reputation” - Dwarves
“Diamond Meadows” - T. Rex
“Sway” - The Rolling Stones
Nothing fancy, just good 'ol guitar-based RAWK! 
Miserlou by Dick Dale
Green Onions by Booker T and the MG’s
coolest songs ever
How come a thread asking for the best song of all time hardly contains any mentions of songs written more than 40 years ago?!
My vote for best song of all time goes to “Er, Der Herrlichste Von Allen” from Frauen Lieben und Leben, lyrics by Antonio von Chamisso, music by Robert Schumann (1840).
Although I gotta admit, there have been some great settings of the Requiem Mass over the centuries.
Let It Be… The Beatles
Touch of Grey – Grateful Dead
You’re right. The best song was by Dylan - the cover version of All Along the Watchtower by Jimi Hendrix.
The second best is She’s Leaving Home by The Beatles. Exquisite.
There’s no way anyone could choose just one favourite song/piece of music, and to list all mine would take forever and I’d still forget some. So here’s just the first few that come to mind, chosen mainly for the lyrics (where there are any!):
“The Sound of North America” Beautiful South
“Something Inside (So Strong)” Labi Siffre
“1812 Overture” (Apparently, when I was a baby, this was the only thing that would stop me crying and send me to sleep!)
“Enter from the East” Jewel
“American Pie” Don Henly
“Hotel California” The Eagles
There’s a song by John Mellancamp (sp?) but I can never remember what it’s called - I can’t even remember how it goes at the moment.
“Fever” Peggy Lee
“(Take a Little) Piece of My Heart” Erma Franklin
“Ain’t No Sunshine” Bill Withers"
“A Queston of Lust” Depeche Mode
Just about anything by REM
“Inkanyezi Nezazi” Ladysmith Black Mambazo
I could go on forever…
But I won’t
Hello In There… John Prine
From A Distance… Julie Gold
And the winner is!!!
Wind Beneath My Wings… Larry Henley & Jeff Silbar
3 way tie
Stairway-by you know who
Freebird-Lynyrd Skynyrd
Black-Pearl Jam