Grand Market - definitely not the best $6-cost card! You'll see when Qvist's list comes out! (and you should vote in it!)
Definitely a super-powerful board though.
Chapel, Fishing Village, Watchtower, Grand Market, Vault are key here I'm pretty sure. FV/Watchtower for a draw engine, Grand Market to supercharge money, and Vault to get Grand Markets and for drawn-deck shenanigans with Watchtower. Chapel to put it all together.
Bishop is a massive trap. The points from bishop are gonna be peanuts here.
You know, I would guess that played optimally, City might also end up being a trap; with a chapeled-down engine, you'll be drawing your whole deck by the time cities get to L2 (when Grand Markets empty), and watchtower will be better draw since you have fishing village for endless actions. And by the time cities get to L3, the game would have piled out already. That's something to definitely play by ear depending on what your opponent is doing, though.