Basically weapons you upgrade constantly, rings and necklaces just find high stat versions (who cares about the armor) and armor replace as you find perfect pieces (this is how I got summoning to 20.) Uniques are fairly crappy, there are only a few really great pieces. Pretty much everything else in the game is usually bested by the best vendor gear (epic at lower levels, legendary mid game, divine later.) In fact once I hit mid game I stopped buying anything but the highest tier gear with sockets and tons of perfect stats, it's so much more powerful and actually can last a few levels until the end of the game where the leveling is totally unbalanced and stupid and one level makes weapons hit about 33%+ harder than the previous 's stupid. Yeah that just shows how powerful sockets are, multiple sockets basically trumps anything that's on the item period (once you start using frames of power on giant runes which become cheap and plentiful around 16, it's kinda gross.) Sallow Man's armor is really good. Alexander's staff with 3 sockets is another rest of the game item, I mean come on that's +9 intelligence +3 from the staff (so +12 intelligence!) and 45% resistance, who cares about the damage it's on a mage that thing is insane. two sockets in a necklace was killer and could be kept the whole game. Mordos Amulet before it got nerfed was awesome.
