Feel free to share your experiences and what you would do differently/change to improve the adventure.
My thoughts, plus some responses to your thoughts, plus some commentary on the adventures you didn't touch on:
Storm King’s Thunder
I have played all the way through is adventure as a player, and I am almost finished DMing it. So far it has been one of my favorites. However, I acknowledge it has some issues, so the other DM and I both put a fair bit of work into addressing those.
The DM who ran it for me started with Nightstone, but replaced the Dripping Caves with an older adventure, the name of which I cannot remember, and skipped Zephyros. We ended up going to Goldenfields and thence to Grudd Haug. We then paused there and "rebooted" with a new set of characters so the DM could use more of the giant lairs. He had us start with a modified version of
Murder in Baldur's Gate that was moved to Luskan. We ended up completing SKT and have since moved on to a modified version of
Scales of War.
For my SKT campaign, I skipped Nightstone and ran "Trouble in Red Larch" from PotA, followed by
Scourge of the Sword Coast. We are most of the way through SKT. The PCs are hunting down some giant lords before taking on Iymrith. So far it's been a blast. That said, some of my players are big Skyrim fans and loved the whole "open world full of sidequests" sandboxy element.
Tomb of Annihilation
While this was one of the best official adventures I’ve run for 5e, there are a few flaws. The driving impetus of the campaign – the Death Curse – is so deadly and fast-moving that it overshadows the rest of the adventure. The best part of the adventure (the jungle exploration and searching for the Lost City) is blasted through to get to the endgame to save the world. Plus there is almost no direction on how to find Omu besides just walking and hoping you stumble into it.
The Death Curse countdown should absolutely be eliminated. Find another less time-sensitive McGuffin.
I wholly agree with you here. I want to run this campaign again as just a jungle sandbox without the Death Curse. I also want to kick things off with the mini-adventure from The Tortle Package. I might introduce the Death Curse later on, once the PCs are high enough level to seek out Omu and deal with it, but I might just ignore it.
Princes of the Apocalypse
My beef with this adventure is its repetitiveness. I don't think I could run it as a full campaign. That said, I
love "Trouble in Red Larch" and have used it to kickstart two separate campaigns now. I remember some people saying they start every campaign with The Village of Hommlet. For me, it's Red Larch!
I have also used elements from this adventure in different campaigns to great effect.
Tyranny of Dragons
Yes, it's a bit railroady. I started it off with the PCs already in town (and they were also 3rd level). I had the right group of players, though, so they didn't mind the railroadyness and had a blast with it. Both adventures struggle with some pacing issues, as well as some incomplete rules issues. I wish the recent reissue had done more to address those, but it sounds like it was pretty half-assed.
Out of the Abyss
I like the idea of this more than the execution. I don't think I could ever run it as a campaign. However, I have used it as a sourcebook for the Underdark and have used bits of it in other campaigns. For instance, I ran "Neverlight Grove" on Halloween as a sort of bad acid trip one-shot during an episodic campaign.
Waterdeep: Dungeon of the Mad Mage
This one is bad, even as a dungeon crawl. It’s not particularly interesting as a campaign. I would recommend using it only to fill in gaps of your regular campaign and drop in the occasional level as needed and re-write it into your existing campaign.
I can't speak to it as a campaign, but I wanted to run pieces of it for a different campaign and a) couldn't find any dungeon levels (that were the right level for the party) that I liked and b) struggled to figure out how to separate them out from Undermountain as a whole. It also sucks that they left out the big shaft in the middle of Undermountain that made it easier to reach the lower levels.
Descent into Avernus
I haven't even read this one yet, let alone run it, but I've read about it, and it seems the glaring flaw here is that the actual Avernus content is sparse. Apparently WotC went the DLC route with this one, relying on the DMs Guild Adepts to fill in the gaps. It also had like 16 writers and apparently that shows as well.
Curse of Strahd
This one is fantastic. It's not perfect, but nothing is. I've both DMed it and played it as a player and really enjoyed it both times.
Lost Mine of Phandelver
Another good one. I think it suffers a little bit in the middle, where the players are encouraged to do a bunch of side quests in order to level up instead of going to look for the missing NPC guy. That's easy enough to fix, though: I let the PCs find him first and then said he needed time to recover from his ordeal, so they went on the side quests until he was well enough to take them to the climactic location.
Waterdeep: Dragon Heist
This one is just plain awful. Worst of the lot. It doesn't know what it wants to be -- a railroad or a sandbox or a tavern simulator. It's got horrible pacing, some of the most egregious examples of railroading I've seen in a long time (that make Tyranny of Dragons look good in comparison), and to top it all off, it's got a bunch of content you probably won't ever use and a terribly anti-climactic ending that will most likely be resolved by uber-powerful NPCs like Lady Laeral Silverhand.
Tales from the Yawning Portal / Ghosts of Saltmarsh
I haven't run all the shorter adventures in these compilations but I have run a few. I think some of the selections are questionable at best, and I also question the value in such straight updates to 5e. Some of the older adventures don't translate that well to modern RPG sensibilities, while others should've had more than just a literal update. Some more thought needs to be put into these if they are going to do any more.