2009 was amazing (if you're looking at music beyond #1s because you can make convincingly bad arguments for every year if you do that).
The XX, Florence + the Machine, VV Brown, Mumford + Sons, Animal Collective, Beach House, Yeah Yeah Yeahs, The Prodigy, Royksopp, Passion Pit, Pet Shop Boys, Paloma Faith, Major Lazer, Noisettes, Lily Allen, Mika, The Leisure Society, Grizzly Bear, Doves, Empire of the Sun, Daniel Merriweather, Biffy Clyro, Bombay Bicycle Club, Bat for Lashes, Basement Jaxx, Arctic Monkeys, Antony + the Johnsons all did great albums.
also had popstars' career highlights:
Lady GaGa - The Fame Monster
Rihanna - Rated R
Katy Perry - Waking Up in Vegas (the album was 2008 but this was her best song
)
Miley Cyrus - Party in the USA (only good song, let's be honest)