Changing styles

In reading the new Marcel Proust biography, as suggested by my editor, Julia. I came across some likenesses in personality; which I won't go into here. 

One thing which did interest me was that a friend asked him for a list of things he looked for in people and the arts, this got me thinking of doing a similar thing for Julia. 
Most of the human qualities would not have changed a lot over time but other likes would have changed greatly.
Obviously some musical tastes have changed as I like 50's jazz music and Django Rhienhardt, but at the same time some have not as I like some of Mozart's work as well as Brahms and Schubert but I am not too keen on Bach as I prefer the more robust styles of Wagner and the East Europeans like Jancek, Bartok, Martinu and the Russian influences.
He quoted writers like Pliny the Elder, Saint Simon, Racine and Flaubert among his favourites among mine are Hemingway, Greene, Shostakovitch and David Eddings. 
The list got me thinking who would you class as modern classics and how  would you evaluate the books? Considering the vast improvement is sales  would you equate a classic by content or sales?
Many people I am sure would include Harry Potter, Twilight, Hunger Games and 50 Shades in the list, yet I have not read any of them, nor do I intend to. 
Does that make me discerning as a reader? In that I don't follow a trend or does it make me a heathen for neglecting what are obviously best sellers?