"intense and selfish desire for something, especially wealth, power, or food"
Cora and Zelena both wanted wealth badly. After that I'd say Pan, since he was just so selfish haha.

Mainly because of all his deals his greed has consumed him.

Cora would be choice 2.

Greedy for power haha. Also Rumpel, Zelena and Pan.

And wealth ;) ^

Pan and Cora for sure.

^^Right! haha

Unlike gluttony, greed is applied to a very excessive or rapacious desire and pursuit of material possessions (cavenging and hoarding of materials or objects,especially by means of violence, trickery, or manipulation)
so yeah Rumple is my choice & what better proof than Mr. Gold's pawnshop!

yeap

Cora was a gold digger who was willing to force her own daughter to marry an old man just so she could have power. The greediest of them all. Followed by Zelena who wanted everything her sister had despite being ruler over the Western land of Oz with amazing magic powers. Then Peter Pan who sacrificed his son for eternal youth and almost sacrificed his great grandson.

Cora, Zelena and Peter Pan