I want many secrets !!
Secret locations, secret quests, secret loot etc to discover ! Some puzzles to solve and best to give more than 1 possible way to solve the puzzle(s) !
To explane I give an example :
Let's say you find a book or an incription market in stone (a rock somewhere in the world) and you see many symbols on it you don't understand ! Now the first part starts here of a (maybe) long quest !
You now can search for NPC's who you can ask about what you found and if you're a lucky one some NPC can show you a way to gain knowledge to understand the symbols .
Suppose you already killed that NPC or you reputation against him/her is too low ... you've a problem indeed ! But their are more ways to find the knowlegde you need ... maybe in a library ?
Next part of the quest is to translate the symbols and discover (for example) that their excist a secret location and the symbols give some "scripted info" (like a rebus: word puzzle) where to search for the location and again, some of just 1 NPC can help you or you can try to find it on your own ... Or you must do tricky things like steal a book or a note, or break in a abandonned house/castle to find what you need, with the unpleasant suprize of undead lurking around the place ...

Maybe another possiblility to find the required info is to use a specific skill on a specific place or whatever (if you invested in the right skill)
Third part of the quest is to finally discover that secret location, well hidden behind a "puzzle of a gate" ... whatever you like

and at least that location have 1 or 2 unique "random" gear/items it was well worth the great effort to do this quest to the final end !
I say "final" because it's also an idea to build up some (1 or many more?) Quest in different levels:
so how deeper (and logically required a longer time to spend on the quest!) the player go in a quest, the better the rewards begin to shine at you
For the example quest I write above :
if the player discover the symbols and find an NPC the player CAN ask for a reward for the info he/she give to the NPC (and so the NPC can go for the quest haha and a bigger reward!).
Or furhter on you discover a book in a library and find a secret little chest with a yewellery item to wear (giving you a skillboost or statboost or whatever). Or you go deeper into the quest and find better weapon in the abandonned house/castle, which required some battles against undead or so.
One thing is certain : how deeper you go in the quest (you needed lots of patiently searching/thinking about ... ), the more the loot start to become bigger and bigger !
I really love Quests in RPG's, quests are for me the power that give me the energy to play and replay rpg's !