>>56394789Between the two, probably Ghost/Dark/Steel just because the Dark weakness probably isn't worth a Ghost immunity.
That said, there's something to be said for Ghost/Dark/Normal. Only weakness is Fairy which is fine since you get to be both Dark neutral and Ghost immune. Losing the poison immunity kind of sucks though.
Water/Dragon/Fairy would also be busted. Water covers Dragon's weakness to Ice (unless Freeze-Dry is used) and Fairy's weakness to Steel, while Fairy covers Dragon's weakness to itself. The only weakness you'd have to worry about is a x2 weakness to Poison.
Electric is also a strict upgrade for any existing Flying types, since all it does is remove Flying's Electric weakness and give a Steel and Flying resist while introducing no weaknesses in return. A Flying/Steel/Electric Corviknight would be a menace.