Crime and Punishment was my worst, kept trying to get through it as I studied it at uni. We read some of it in class, which I think is all I read of it. But never read it through and had to look up how it ended. And now I can't even remember what I looked up. I think I've blocked it out. I had to do an essay in an exam comparing it to Brothers Karamazov, which was fun, given I only got about a chapter into that one.
I am surprised so many people have mentioned A Tale of Two Cities - it has a home on my shelf as one I loved and won't give away (but will never read again as too sad!). I think the only other Dickens I've read is Hard Times, though, as we had to study the industrial novel at A level. I quite enjoyed that too, but I think the bleakness of the TV adaptations of the others I've seen have actually put me off.
I haven't finished The Mill on The Floss (and would in fact have to start it again cause I can't remember what happened), but I haven't given up on finishing it just yet, as I actually loved Middlemarch.
I can't get through any D.H. Lawrence or Thomas Hardy. It's the women in Hardy - cannot recognise anything about them.
I don't have the mental capacity to read the real classics these days, with the exception of Persuasion, which I read about once a year - it was my first Austen and will always be my favourite.