pop·u·lar·i·ty/ˌpäpyəˈlaritē/
Noun: The state or condition of being liked, admired, or supported by many people.
Recovery was the best selling album of 2010 in the United States and number 2 worldwide in 2010 just behind Lady Gaga's Fame (Monster) album.
Nothing to do with which album is considered to be better as you are discussing popularity.
Kanye West's College Dropout is superior to Encore yet Encore sold 6 million albums worldwide in the space of a month whereas The College Dropout sold 2.3 million in that entire year does that make Encore the better album? hell no, never but it was more popular.