What is your favorite type of loot? consequently, what enemies are your favorite type to fight because of this, and what are your favorite places to explore?

Dwarven enemies. They drop Dwarven Oil, which is useful for magicka potions, and gemstones and soul gems. Centurion dynamo cores are cool as well.

Not sure about enemies, but in Morrowind I like to loot the barrels and chest.

There is always gems and stuff in there