Mine is definitely http://www.uesp.net/wiki/Oblivion:The_Forgotten_Chests_of_Pale_Pass. Loved that little scavanger hunt!

Which one(s) did you like best?

http://www.uesp.net/wiki/Oblivion:Bittneld_and_Emfrid I'm a svcker for romance. You need the Unofficial Oblivion Patch to make it work, though.

I've often completed the Forgotten Chests of Pale Pass but never completed the Bittneld and Emfrid quest.

I liked the one where you collected the notes from the guy who became a lich, I forget which dungeon it is now though.

That would be Lost Boy Cavern

Yes that one! Goodness it has been so long, I love this game.

I posted a Mod on the Nexus ( where I'm called 3rdtryguy ) which greatly improves the Ring of Perfection. That quest is a big pain, so I made that ring actually worth finding and wearing. Now everything is +25 instead of +10. Maybe that will make this quest even more enjoyable for you?