Vanilla: Gnomeregan, Diremaul, Wailing Caverns. TBC: The Black Morass, The Slave Pens, The Steamvault, The Underbog, Auchenai Crypts. Wrath: Halls of Reflection, The Nexus, Trial of the champion, Utgarde Keep. Cata: Deadmines, Halls of Origination. MoP: Stormstout Brewery.
Generally I didn't like the theme of most TBC dungeons nor did I play during TBC, but I bet if I had experienced those difficult dungeons in its prime, I would probaly have more love for the dungeons.
Wrath was overall meh, only a few good dungeons, all were easy so I base it mainly on whether I was about to puke or not if I get queued for certain dungeons.
I really enjoyed Cataclysm dungeons the most. I really, really liked the difficulty at the start of the expansion and the only dungeon I never finished prior to the nerfs were Blackrock Caverns (I curse Corla everyday for the painful pug experience I had with her).
Halls of origination was way too long with too many bosses. I didn't like old deadmines nor do I like current deadmines, not even for it's difficulty.
As for Stormstout brewery, I believe it easily makes it to my top 1 hated dungeon ever made. It's a boring, mindless dungeon. The bosses are so god awful that I almost fall asleep everytime I do the dungeon.
I'm afraid we'll NEVER experience Cataclysm level of difficulty in terms of dungeons, now that blizzard has Challenge Mode, which I love, but I never had as much fun with dungeons than I had with cataclysm dungeons. They should've kept them at the difficulty since eventually people would outgear the dungeons.