50s: Jerry Lee Lewis
60s: Yardbirds
70s: Thin Lizzy
80s: U2
90s: Soundgarden
00s: Strapping Young Lad

There's absolutely no way I come up with just one for each decade so here are several for each decade instead:

50s: Eddie Cochran, Chuck Berry, Charles Mingus

60s: Esquivel, Pink Floyd, Miles Davis, Beach Boys

70s: Television, Bauhaus, Stevie Wonder, Lou Reed

80s: Foetus, Alien Sex Fiend, The Cure, Joy Division, Tom Waits, Ministry

90s: Trans Am, The Church, My Life With the Thrill Kill Kult, Swans, Mr. Bungle, Godflesh

00s: The Microphones, Kill Me Tomorrow, Secret Chiefs 3, Matmos

Which has been the best decade for music?
 

50's / Elvis, Chuck Berry and Rock & Roll

60's / The Beatles and The British Invasion, Motown, Psychedelia and the beginnings of Heavy Metal

70's / Arena Rock, FM Radio, Punk, Drugs and Rock & Roll. And disco

80's / New Wave, House, Hair Metal and MTV

90's / Grunge, Alternative, RockCountryPop and Boy Groups

00's / Pop Idol, The X Factor, American Idol, everybody reforms and every possible Genre and subgenre imaginable

50's / Elvis Presley>Jerry Lee Lewis
60's / The Kinks>Velvet Undergorund>Beatles>Dylan>Byrds>Zombies>Who>Stones .
70's /David Bowie>Neil Young>Pink Floyd>Led Zeppelin.
80's /The Smiths>Prince>The Cure>REM>Sonic Youth>The Replacements.
90's / Pavement>Wilco>Radiohead>Pulp>Tindersticks>Blur>Be lle & Sebastian
00's /The National>TV On The Radio>Modest Mouse.

50's-Charles Mingus
60's-Jimi Hendrix Experience
70's-Frank Zappa
80's-RHCP
90's-Clutch
00's-Mastodon

My Ying and Yang for each decade

60s: Stones >< Beatles
70s: Black Sabbath >< Bowie
80s: Slayer >< XTC
90s: Pantera >< Radiohead
00s: Mastodon >< The Shins

As some groups crossover decades, I`ve put where I most like their stuff.

50`s Chuck Berry, Elvis
60`s The Doors, The Beatles, The Who, Jimi Hendrix Experience.
70`s Led Zeppelin, The Who, Deep Purple, Black Sabbath, Yes, Rush, Wishbone Ash, Cheap Trick, Styx, Kansas, Fleetwood Mac, David Bowie, Aerosmith, Alice Cooper.
80`s Fleetwood Mac, Kate Bush, Toto, The Cars, The Tubes, Slayer, Megadeth.
90`s Nirvana, Sepultura, Pantera, Soundgarden, Meshuggah, Monster Magnet, Dream Theater, Radiohead.
00`s As of yet undecided.

50s - Jerry Lee Lewis
60s - The Beatles
70s - Journey/Foreigner
80s - Damn, so many to choose from! Well anyway Exodus/Overkill/Megadeth/Iron Maiden/Judas Priest/80s Pantera/Def Leppard/Bon Jovi (like them or hate them, they made some very fun and catchy music during the 80s)
90s - Paul Van Dyk/In Flames/Daft Punk
00s - Deadmau5/Benny Benassi/Sonata Arctica (pre Unia)

50's - Bing Crosby, Miles Davis, Sun Ra

60's - Fever Tree, Quintessence, Golden Earring

70's - Yes, Terry Callier, King Crimson, Rush, Camel, Return to Forever, Gentle Giant, EW&F, 10cc, Comus, Can

80's - It Bites, Talk Talk, Level 42, The Rippingtons, Talking Heads, Mr. Sirius

90's - Faith No More, Goldie, Mercury Rev, Screaming Headless Torsos, ATCQ, Global Communication, Jellyfish, Mansun, Ozric Tentacles

00's - Pain of Salvation, maudlin of the Well, eufonius, Mew, Moon Safari, Coil, Fleet Foxes, Opeth, Six Organs of Admittance, The Kilimanjaro Darkjazz Ensemble, Thievery Corporation

Trying to limit it to one per decade.

60s - The Beatles
70s - Pink Floyd
80s - Skinny Puppy
90s - Fugazi
00s - Pinback

Pretty predictable, I guess. Seems like this decade is the hardest to decide on...surprisingly I have more albums from this decade than any other. I think we figured that out in another thread. So I guess it's not so surprising.