2010 deserves a mention in my book; Mario Galaxy 2, Mass Effect 2, Xenoblade Chronicles, Vanquish, Donkey Kong Country Returns, Halo Reach, Call of Duty Black Ops, Alan Wake, Bioshock 2...
That said I gotta give the all time win to 2007, the amount of GOTY calibre games it squeezed into just 12 months was bonkers.