My favourites are:
A Tale of Two Cities - because who wouldn't like a novel that has a character who records the names of traitors in her knitting?
Barnaby Rudge - a tale that includes some great characters, a duel and my favourite pub in literature - The Maypole.
Our Mutual Friend - contains an intricate web of characters and, in my opinion, the best delivery of justice to a villain.
Martin Chuzzlewit - I grew up watching the BBC adaptation of this but I love the story and the eccentric characters of Mrs Gamp and Montegue Tigg, and the main character has a cool surname.
I could add others but I suspect I may end up adding them all, which would sort of defeat the object of having a short list! Comment below and let me know what would be on your list.