Probably better placed in players questions than player guides.

That's a very general question. It depends on your build, playstyle and class, really. If you're main weapon is destruction staff, then maybe you'd like something close-range in case enemies move in. Healing staff is useful, but it might be more efficient to party up with a designated healer, rather than going for a hybrid DPS/healer build. You might not want to spread your skill points too thin.