So I'm the only one that gets all into the mini quests that pop up in Nordic ruins from time to time, with journals and notes telling the events from the writers POV that occured from previous eras.. I just completed a ruin with a quest about people battling a cult from the FIRST era. I save all the journals, books, notes from all my journeys. These stories are interesting. As for uniquity, Oblivion has empty bland ass dungeons with no reason to really explore them. Yeah Alaswell for forever stand out as one of the first INTRIGUING quests that game has to offer, but the same can be said about Vilverin, but nothing else after that. For Skyrim, everywhere I've gone I felt I have no wasted my time. There has always been some kind of HISTORY to these places.
I provided two examples, and the lore is best part, but dungeons get dull really quickly, most unique I saw were Eldergleam Sactuary, Dogfighting Pit, snd sunken cove place. As for Dwemer ruins, some are awesome, others are meh. I'm talking about non-dungeons and they're actually interesting.