Greed - Hook (While he was a pirate, his trademark villain thing was selfishness)
Envy - Zelena. Why would it not be Zelena? It's Zelena.
Sloth - Arthur since even though he wasn't lazy per se he did abandon everything over a dagger and become a horrible king.
Lust - Cruella maybe? Cruella always wanted more stuff. The first time we saw her in the LWM was when the police were confiscating her stuff and Gold asked her where she was going with these paltry material possessions, to which she responded, "To get myself some less paltry possessions!" Plus Cruella fits somewhat in the romantic sense here. Think her in the Underworld with James.
Obviously for the sins, many characters can fall into multiple, but I tried to choose the most major characters that clearly exhibit one of the sins as their main thing. So here they are, with reasoning:
Lust - Hook - Lust is all about desire for pleasure, and Hook looked for pleasure in almost everything he did, from seeking revenge on Rumple (the pleasure of killing Rumple), to his romantic interests (the pleasure of the love of Milah and later Emma).
Gluttony - Cruella - Gluttony is all about consumption, and no one consumes more than Cruella. From fancy food and drink (the gin!), to jazz music, to the pelts of animals, Cruella consumed it all with ruthless abandon. She even consumed (ie killed) her mother's husbands.
Greed - Rumple - Greed is all about hoarding wealth, power, etc., and Rumple was great at that. His many deals always got him exactly who or what he wanted, although looking at his castle filled with things, it seems many things weren't even gotten for any other purpose, other than so Rumple could have it, and someone else couldn't, which is about as greedy as you can get.
Sloth - Maleficent - Sloth is all about not doing things, and Mal basically gave up on living after Briar Rose bested her, being in a drugged out state, until Regina came along and convinced her to take action against Aurora, many years later. Once that was accomplished Mal was content with once again staying in her castle, as she didn't even want to fight Regina for the Dark Curse ("Must we?"). Plus, Mal's great evil plan to best her enemies is to put them in a coma like sleep. Even her evilness is lazy!
Wrath - Regina - Wrath is all about getting way too angry, and boy, does Regina ever get angry. One wrong move and she'll snap your neck or order a whole villiage destroyed. Her go to spell is a fireball, for goodness sake! And let's not forget that Regina spent years trying to get back at Snow for spilling a secret, when Snow was like 10 at the time in question. If that isn't misplaced anger, I don't know what is.
Envy - Zelena - Envy is all about being jealous of others. Zelena is certainly jealous of her sister, Regina, who she things got everything that Zelena herself deserves. Not a one trick pony, however, Zelena often gets jealous of others. Glinda had inducted Zelena into the witches coven, and yet Zelena was still jealous when Dorothy showed up. This is probably the most obvious of all the sins, as Rumple confirms Zelena literally turned green with envy.
Pride - Cora - Pride is all about feeling you are above others, either in brains, looks, or both. Cora certainly feels she is both smarter and prettier than even a princess, despite being the daughter of a miller. She almost gets one prince to marry her, but when that plan falls through, Cora finds another man who will fit the bill. Cora will make people kneel to her one way or the other. Even an unplanned trip to a strange world is no problem to Cora, she simply becomes Queen there. Cora hates when people see her as just a miller's daughter, because she is "so much more".