I am not an expert on ordination but its the opposite than what you think. Hand laying is done for the minor ranks (If I remember correctly) and just the cross for the priests. The main difference between the two ordinations is that the Bishop blows into the mouth of the Priest and the Priest only to receive the Holy Spirit as Jesus "breathed on them, and said to them, “Receive the Holy Spirit"". The Bishop does not blow into the face of any of the ranks of deacons and I think that is why the hands are laid on them.
According to H.G. Anba Mettaous's article : http://copticchurch.net/topics/thecopticchurch/sacraments/7_priesthood.html
, the reader is tonsured (hair clipped), but does not have hands laid on. "The bishop clips his hair, however, he does not lay his hands on him" I remember the cross on my head in H.G.'s hand.
Deacons, priests, and bishops receive the laying on of hands. Chanters and readers, as minor orders, do not. Subdeacon is a bit unusual--generally counted among the major orders, but according to this article, without the laying on of hands.
The prayers for a reader say that it is the first rank of the priesthood, and this article says that the bishop does breath in the face, though I don't remember that happening... I could be wrong. The preist is breathed on 3 times.
Laying on of hands is definitely for priests, and just the cross for minor orders.