Boyd's output in the U18's, AIS v Collingwood reserves, and in the champs, looks to have been a higher and also a more consistently high level than the likes of McCartin and Wright have put together so far and he doesn't seem to have any chinks in his armour.
Boyd is possibly the most dominant (for someone who plays KP and is 193cm+) to have come through the juniors this century, actually. Hard to remember anyone else remotely similarly sized who was as consistently dominant as he was. Patton was possibly at a McCartin-type level, but with the extra height, versatility (can play some ruck I guess) and better kicking for goal.
Out of those 4, at this point in time I'd be wanting Boyd and Patton in that order and then it's a bit of a toss-up as to which order the other two go. This is all going by what I've seen of Patton and the results the other 3 have produced though.