This post has been here unanswered for a couple weeks so I am gonna try and tackle it.
The first problem is that what is good or worthwhile to me might not be to you. In tier 2, I didn't bother with the AQ series at all since I felt that player crafted, (rares), had better stats at that level. But, I don't know what you can afford.
Second problem is that you don't say exactly what you're looking for or what your trying to upgrade from. You might consider the gnome inside the bank in the Baubleshire. He offers a quest line, (3 or 4 quests), that has an end reward of a really nice head piece for mid 20's. There is also a lot of really good jewlery available in T-Steppes. You might try the "Wandering Auger", (on the T-Steppes docks) with her three quests. Or "A message for Kitty" from Amy Bhorgese who is standing inside guard tower 3. There is also a centaur called "Warder of the Fields" down in the South end of the zone. He has a bunch of different quest lines, (7 in all), and each group ends with a nice reward. One of them is a good- brestplate.
Third problem is that since the AQ series is available for just that range of levels, there isn't a lot of other great gear out there to be quested for. When you reach lvl 30, the quests in EL will be real good for you. There is a series of simple chest dropped kill-quests here, redeemed by a guy standing on the EL docks. Each quest will net you your choice of several pieces of armor, (6 in all).
And the final problem is that since this post is now 2 weeks old and the brokers are back up, the point is probably moot! Oh, well...