These are both very awesome items and very hard to obtain. But to say if you were to obtain them which would be better. The Wand of Orcus has a lot of Necromancy features which would be awesome for a Necromancer and the random beneficial properties are great and will not break but it also comes with the random detrimental effects as well. Not to mention it's sentient and wishes only to serve Orcus. The Staff of the Magi on the other hand has a lot of charges and has many positive features but has the danger of breaking from overcharging or if the player breaks it.
Your vote: Wand of Orcus