Sea Hag is unignorable in any strategy. (And actually, Chancellor isn't irrelevant as it helps you play your Sea Hag faster, and if you flip your deck, you won't automatically get the Curse in your next hand. I'll assume you don't want any strategies which require the other 7 cards to actually be Chancellor.)
A: Even in the absence of cursing attacks, a Village/Smithy engine alone doesn't beat BM/Smithy. Adding Curses you can't trash isn't going to help, so it's clear you have to play BM, with a Sea Hag/Silver (or Sea Hag/-) opening.
B: Watchtower can defend against Sea Hag, but not 100%, and you can't trash the Curses once they're in your deck. Probably Sea Hag/Silver or Sea Hag/Watchtower are both considerable openings, but you still have to play BM, for the same reasons.
C: Workshop isn't enough of an engine enabler, and is actually even less relevant than Chancellor, so this is the same as A.
WanderingWinder played a game against Stef with a five-card kingdom - Village, Smithy, Spy, Develop, and Market. Stef just about won, but all of these components are important, and the engine would never have worked without Spy's attack and filtering, Develop's trashing and gaining, and Market's +buy. Generally, if an engine has neither +buy (or another way of gaining multiple Victory cards per turn), nor an attack to play every turn, it will lose to BM.
