You sure use that defense a-lot.
Yet you fail to see it apply to your 'faves'. Not looking at the sales, but the part where opinion does not determine quality.
Let's take Chihaya for example, just because you and the 3-4 other major 'other anime' posters love it, does not make it a masterpiece. The 'other anime' crowd is a microcosm of the entire anime-consuming world. Many people will not enjoy it due to the unique, dull/boring(Karuta battles/matches) qualities that anime possesses.
That should not take away from your enjoyment of Chihaya, or SAO(that many a fan will not care or value them in the same regard you do), nor require you to defend them.
At the end of the day, as you love saying, all you, I, or anyone can say is 'opinion,' not fact.