There are more fan favorite or critically acclaimed anime you could have put up there (Fullmetal Alchemist/Brotherhood, Cowboy Bebop, Ghost in the Shell, Code Geass, Dragonball, etc) that still fall under the category of mainstream. I'll go with Naruto because of the nostalgia. Plus, SAO really isn't much of contender with everything else on the list.
That's trite logic but contrary to what you might believe many people on this forum don't even like Naruto that much. There are also many members here from OnePieceBay which died.