1) Which classic do you think is truly great enough that everyone should read it?
2) Which classic do you think everyone may as well skip?
I'd be hard-pressed to answer those myself with just one title each. For #1 do I choose Jane Eyre, Les Miserables (abridged), Middlemarch, or what exactly? If Lord of the Rings counts, I might well choose that. And for #2...well, generally I've seen the merit in nearly all classics I've read, so I don't like to slam anything too hard. But I've found Faulkner very hard going (I think it was The Sound and the Fury; I don't even remember now), and Hemingway choppy and dull (he's better in short form), and I waited 200 pages for a plot to arrive in On the Road before giving up, and I've wanted to strangle the majority of Thomas Hardy's characters, and Stranger in a Strange Land plummeted from a very cool setup to a wanky free-love mess. So there are some possibilities, as to my own answers.
But I want yours instead. And I don't want this to turn into a catfight, so be nice. Every reader's tastes are what they are, and it doesn't make them an idiot. I, for instance, married a very lovely man who owns pretty much every book ever written by Hemingway and won't sell them despite my most sweetly phrased suggestions. (I think Hemingway may be a "guy thing."*) Yeah, so: go ahead, answer!
*Just know I'm going to catch it for that remark. From you folks, not from my husband.