Duke looks weak here to both Rabble and Bishop. I also had the idea of getting up a big engine with minting and trashing a gold (more likely two, possibly more) every turn. I guess haggler works there, too. The question is, is it fast enough?
Wishing Well counters Rabble sort of, but man, if you are in the situation where you are actually doing that, you are either right about to end the game in a win, or you're probably in very bad shape.
So, I think you have to go for this bishop kind of thing, eventually at least, and probably at least in the mirror you'll want a haggler, as you'll need/want to go for provinces, and even keeping at least some of them, though this gets highly into the exact game state of the endgame you get into, and you can't totally plan it from the start. So how do you get there? I think you want Ironworks and... maybe wishing well? Try to spike an early mint. Grab a bishop to clear estates, silvers if/when you need them, and farming villages. Haggler with the next 5, looking to get golds and rabbles until you have enough, then transition for bakers. Bakers help you keep more green back. A LOT of how you build depends on how the game goes. And probably you open silver > wishing well. I love the early wishing well so much, but...
Baron, I don't think you particularly want most of the time, though maybe if it gets to the point where you really really need +buy, you go there.