This list was comprised by Metacritic, which takes the critics reviews, compiles them, and "adds" the scores together.  Pretty interesting list.  If you check the link there is more of a breakdown as well as highest reviewed albums by genre.
For Indie/Alternative
1	Sleater-Kinney	
2	Spoon	
3	TV On The Radio	
4	White Stripes	
5	Sufjan Stevens	
6	Animal Collective	
7	Drive-By Truckers	
8	Lightning Bolt	
9	Sigur Rós	
10	Bjork
Hip-Hop
1	OutKast	
2	Dizzee Rascal	
3	Kanye West	81.8	College Dropout
Yo Kanye, we’re really happy for you, but OutKast had one of the best decades of all time.
4	Missy Elliott	
5	The Roots
6	Murs	
7	The Streets	
8	Nas	
9	Ghostface Killah	
10	De La Soul
Pop/R&B
1	Solomon Burke	
Not bad for a man whose age is close to his average Metascore
2	Me’Shell NdegéOcello
Her stellar December ‘09 release is not included, since it had just 4 reviews at press time
3	Erykah Badu	
4	Al Green	
5	Mary J Blige	
6	Norah Jones	
Come Away With Me trailed only The Beatles and ‘N Sync for top-selling album of the decade
7	Shakira	
8	Ne-Yo	
9	Alicia Keys	
10	Keyshia Cole
Singer-Songwriter
1	Bob Dylan	
2	Tom Waits
3	Sufjan Stevens
4	Iron & Wine	
5	Sam Phillips	
6	Richard Hawley
A former member of Pulp, Hawley is one of the top British singer-songwriters working today
7	Andrew Bird	
8	Neko Case	
9	Richard Thompson	
10	Rosanne Cash
http://features.metacritic.com/featu...of-the-decade/