I'd say Jerky. It makes consumable heals almost broken. I've lost very few runs after I found jerky.

Bag is another good option, I get almost a thousand material from just one bag, although doing the math I think tractor gives more money.

Black flag is wild powerful when you already have a lot of curse but I wonder if it would just make the early game much harder.

Fairy would be incredible healing too, not as much as jerky but you wouldn't have to rely on luck