[maskedoffender]

They're both about wealthy enigmatic characters (albeit the count of monte cristo book doesn't keep the count's purposes a mystery) who throw extravagant parties. Both characters seem emotionally distant and turn out to be excessively obsessed with the past. They both feature a lot of tragedy and revenge and the titular character meets their love from long ago who is now married to someone else.

They both have connections to the criminal underground, they both anger the husband of their love causing death.

Not exact duplicates by any means, but the similarities are there.

[Thibi2000]

Having similarities doesn't mean something is a crappy version. What's behind the similarities is different as well, for example the reason for their obsession with the past. I'm sure you can find similarities between many stories when you do it in such a vague way.

Besides that, there's more to those books than the main plot. I always assumed that TGG is this well regarded because of themes it handles and how they're presented by the story of Gatsby. The same goes for The Count of Monte Cristo. I find them to be too different to call on even a version of the other, let alone a crappy one.

[maskedoffender]

I think that revenge and intricate interpersonal plots should just be avoided unless someone intends on outdoing the count of monte cristo. Maybe it's unreasonable but that's how I see it. I guess really the only things I appreciate in the great gatsby are the things in it that remind me of the count.