In an ideal situation where you are using a belay device in guide mode off of the anchor, I would use a z-pulley, mostly because it would be so fast to set up.
Consider your position before setting it up,
at this point all it takes to set up a 3:1 z-pulley is to attach a prussik onto the climber rope with a carabiner and clip the carabiner onto the belay strand like this,
Once the prusik has gotten high enough that it you can no longer pull in rope, let the belay device hold the rope in guide mode, and reach down and push the prusik as far down the rope as you can.
This would be rather slow since you can't pull in very much at one time.
The other thing to consider is if it wouldn't be easier to lower the person instead of pulling them up the rock.
I could see this being used where you really need to get to the top and your follower is struggling to get past the crux of the route.