I was wondering if all the equipment rewards from quests scale with the level you are when you turn them in? If so, I would think there are some quests you should wait to turn in until you are higher levels.

I believe the armor sets / rewards from doing certain guild quests are scaled to your current level. Which means, yes, if you complete a guild chain pre-lvl 20 you will receive a lesser quality version of the exact same item you would receive if you were say, in your 30s. I personally really don't like this. I understand Bethesda's reasoning in doing this as to not provide you with extremely good gear while still at an early lvl thus making the game too easy too early. It just seems like there should have been a better solution rather than dumbing down some of the cooler gear.

I understand that for sidequests, but it really bothers me in the guild quest lines. If I want to play a thief character, I should wait until I'm 35+ or so to do the thieves guild quests? That's just silly.
To the OP: The rewards from Daedric Quests seem, as usual, not leveled. Don't know about any others.

There's been a few threads talking about this very issue. What I have gleaned from reading those is that there are only about 5 sets of armor that are scaled to your level, and there are only three tiers to which each levels. I do not know the cutoff point for each tier. The weapons list was considerably longer regarding item scaling. There is a website that has a list of all of the known scaleable items, but I'm sorry, I have forgotten what site.

Item/level scaling svcks. The game is still really well done, and I am enjoying it a lot, but the whole scaling issue was what turned me off to Oblivion completely. Thankfully it has been improved for Skyrim, but I'm baffled that it even made a return. I assumed Bethesda would have learned from past mistakes and created a better system.

It's exactly like oblivions scaling.

Daedric Artifacts aren't leveled, that's for sure.