Arguably. While Culling is one of my favorites, from both a lore and gameplay perspective I found Black Morass pretty boring. I understood why it was important to the timeline to ensure it went off without a hitch, but the dungeon itself was very story-light and was more or less just you waiting on spawn windows.
End Time wasn't so much about us upholding an atrocity as preventing one, and it's one of my favorite Caverns of Time dungeons. Seeing what could happen if we fail, I feel, is a much more effective method of explaining why the adventurers make so many apparently-bad decisions that work out in the end Because Plot--for example, the events from The Blank Scroll would probably have been much more effective as a storytelling tool if it'd been represented ingame not as the result of some all-powerful, reality-shifting relic, but a dungeon wherein we're shown a timeline where Anduin never shattered the Divine Bell because the SI:7 team was successful in sending him home, leading to Garrosh's Sha-empowered superorcs turning on the rest of the world, forcing a last stand at Stormwind Harbor and culminating in the adventurers being teleported back to the proper timeline after the last stand crumbles.