Neilson! only because i have not seen enough of him. i'll have an opinion soon. so far i like his shot.
Not much question that Kaufusi is going to be a major contributor, though there is still uncertainty about where he will fit in the rotation...but in the rotation we will see him and likely at Mika's level by March.
update:
Neilson looks pretty good, will probably get quite a bit of time before Aytes' 12/20 debut. Nixon is also looking good.