One surprising sidequest apperared to me when i was passing by
. It had some interesting ideas to beat it.
Also, another particular quest, although i think its connected with the MQ, but you don't have to make it if you find other ways around it make me think about Deus-Ex.
I really didn't want to do it the "obvious" way so i stormed in guns blazing. Beeing "the good" guy. Surprised how i earned Karma doing it.
It seems that most solution has different way to solve it. And pointing out one particular "grand" quest is hard. Most interesting quests i stumbled upon.
I think however that doing research for the "book" was one of the best way to get introduced into the world.
My findings is that the sidequest isn't "good" on their own. But when they appeared for me i did enjoy them immensly. They added to the universe and the experience.
Many quest was connected to and referred to by other quests. It made everything more beliveable. BUT i also think that it will differ from person to person. How you choose to do and play it. I followed the mainquest pretty strahightforward and always felt like i had to replay the game to experience it so i didn't bother on exploring to much. That i wanted to do in my next play through.
(Its hard writing about good quest since i don't want to mention them since then, if i had read about them i would probably gone: Ah, now that is that quest!
)