I'm someone who loves
Tyranny of Dragons. It's in my
Top 5 adventures.
It saddens me that most DMs don't connect with it. (But it certainly has a following - it's not just me!)
Part of what I like about Tyranny is the ambition. It keeps ramping up, and it properly treats the high-level adventurers as important people, who even the Council of Waterdeep listen to. But still, it's got holes, especially with how to finish the entire saga.
After that, Princes of the Apocalypse and Out of the Abyss are big, ambitious adventures as well. They're not thinking small. They have problems, and probably require some reworking by the DM, but all the bones are there. These first three adventures are also doing stuff you don't often see in RPG adventures. I've run Tyranny three times, and I'd love to go back to Princes or Abyss again to see what happens now I'm even more experienced as a DM!
In contrast, I don't find The Shattered Obelisk ambitious at all. Or rather, the ambition of the concept is not matched by the execution at all. Vecna is ambitious, but there's such a mismatch between the Vecna storyline and the Rod storyline that causes a lot of cognitive dissonance. People
love the idea of doing a quest for the rod parts, but so many of my contacts have thrown out the individual sections of the adventure since they can invent something better.
Descent into Avernus is the nadir of Wizards' horde of freelancers strategy, and from what I've heard, was a very, very troubled production. It's got a great concept, but while the conclusion reads as if the players have a lot of freedom in the middle act, it plays as some linear stories without the deal-making you'd expect where you could go between factions and play them against each other. I can see some groups connect with it, but for me it's just not working.
Cheers!