Often times, as quest rewards, I end up with a unique item. Most of the time, I take a look at it and go "meh, this is garbage compared to what I have now" and mark it as junk.
However, many of these items have special properties that overcome their junk stats. I've taken to checking the wiki every time I find a unique quest reward just to make sure it doesn't have any hidden, super useful properties, unique abilities, synergistic tendencies, or glitches that make them invaluable. Other times, they're just really junk.
Trying to figure this out is really irritating though, and I've sold items only to find out later that they were so awesome and I've lost my chance at having them. Other times I've filled my inventory with quest rewards that I never could quite understand the usefulness of. It would be nice if there was a summary of the really critical ones to keep.
What quest rewards should I hang on to long after their acquisition? What unique items should I keep, regardless of their stats?