There are an amazing number of ways in which to judge a body of written work. How does it make you feel? Is it well edited? Did it spark your imagination? Great cartography / illustrations? Fantasitc supporting material? Illuminating content on cannon? And on and on and on...
How does one even begin on a task such as this? It's overwhelming. I sort of baited James and asked him for his list. Now that's cheating I suppose... In that James is very well entrenched in his niche and for a person like him to list "his" top 30 greatest modules would not be nearly the stretch that it would be for a guy like me. James has a well documented history of "what" he likes and why he likes it. His challenges are an excellent indicator of such.
Anyway, I suppose what I'm trying to say is that, if a guy like me were to construct such a list (and it wouldn't be all that difficult) it would be based on purely experiential credentials. It might start something like this:
- Lost Caverns of Tsojcanth: Fantastic module based on the notion that a "dungeon" is other wordly. It is a "node" and to enter it is to enter a world unlike that which was left behind. That and the new material introduced in it set a gold standard for modules that followed; If you can't come up with a new adventure (i.e. Not a standard dungeon crawl), then you'd better surprise your players with some new material.
- Hall of the Fire Giant King: Location, location, location! This place dripped scene and setting. It was the penultimate WWX knockdown, drag-out battle of the titans. The personalities in this module were stupendous: Obmi, Fruppe, King Snure Iron Belly and lest we forget, the DROW were introduced to us here, Eclavdra anyone? Great stuff...
- Caverns of Thracia: When someone talks about a "dungeon" this is what springs to mind. Paul Jaquays was a master at constructing a whole out of apparently disparate parts. This place had it all, and for a piece put out in 1979, it did a pretty spectacular job of filling in the niches while still allowing the GM to freely improvise and create where he or she saw fit.
This could go on...but it would likely be an exercise in futility. You don't know me. I don't have a body of "work" out there that you can reliably base a response upon. James does. I'm eager to see his list. ;-)