I don't know where you're at in the game but nightmare campaign is definitely not the best place for improving your gear. That's gonna be dungeons and forge, specifically dragon if you're earlier on in the game. 

If you can make Perception gear, do it. Grinding FW, even low levels, is important to get this gear. For a new and midgame player, there is nothing better than a set that gives you both speed and accuracy bonuses.

So while Krama is right, don't focus on gear sets too much, the sets with speed and accuracy bonuses are absolutely awesome for finishing content.