I realise I didn't post comments or a ranking update on this thread following the completion of my 12th Dickens novel, Martin Chuzzlewit, which I concluded a little while ago.
Martin Chuzzlewit took me a long time to read, and this was probably because it was the 'hardest' to read of all the Dickens I've tackled so far. And I found it hard for a number of reasons, not least because it doesn't have a central character, or much of a plot. The lack of a central character was an interesting approach by Dickens - there are chapters concerning different characters, but one doesn't dominate over others, and we are not invited to have sympathy with any one character particularly. This is, of course, why the plot is rather loose too; if you don't revolve the story around one character, you get multiple strands being developed in parallel. Dickens does tie things together at the end, and it's a reasonably satisfying ending, but that said, it's rather too neat and tidy, given what precedes it.
Another problem with the book may be that Dickens can't seem to quite decide what sort of book he wants to write. It's part biting satire, akin to Mark Twain (in the American-based sections), part comedy (but in a dry, droll, smile if you like, kind of way, not wholeheartedly amusing as Dickens can be), part social criticism, and part character study. But not quite any of these things either. As comedy, it fails for me - there are amusing passages, but the hypocrisy of Pecksniff (which is supposed to be humorous) is too irksome, and the book as a whole is just too sad for comedy (I agree with Chesterton here). Mrs Gamp has her moments, but considering her position as a famous example of Dicken's memorable eccentrics, I found her rather underwhelming and unconvincing. In fact, this book lacks the kind of caricatures that draw me in to Dickens.
Overall, I thought it was rather a weak for Dickens - a slightly disjointed, and overly long book (I think it's his longest). It had its moments to be sure, but it doesn't trouble the upper tier categories in my ranking. So, I can update the ranking lists like this:
Category 1: Dickens' finest work, combining mature writing, exceptional characters and deep plots
Bleak House
Our Mutual Friend
Great Expectations
Category 2: Classic works, with great characters and highly memorable scenes, but flawed in some way
Dombey and Son (loss of a major character early on was a strange choice)
Hard Times (less 'Dickensian' than other books, otherwise great)
The Old Curiosity Shop (two story threads move apart for Nell's journey; but best Dickens villain perhaps)
David Copperfield (flabby middle is poorly paced, with a disjointed storyline; but first and last third are great)
Category 3: Lesser Dickens: good reads, and still recommended works, but not to be prioritised given their imperfections
Oliver Twist (coincidences abound; terrific characters but plot difficult to accept)
Nickolas Nickleby (somewhat light plot doesn't engage the reader as much as his best; lacks the eccentricity of his best works)
A Tale of Two Cities (less intertwined Dickensian plotting and less strong on character, but has its moments, certainly)
The Pickwick Papers (early style, with many deviations and inserted tales (not all great); but terrific characters and a good end)
Martin Chuzzlewit (no central character, slightly weak meandering plot, a no-mans land between being comedic and serious)