I think Lundvqist in his prime edges out Luongo in his prime, but only slightly. We could just call goaltending a draw then, in which case team alternate still looks better than team captain.
What I was thinking about in my first post is, to use current goaltenders for the sake of example, if you did an extreme example of putting Stuart Skinner behind team alternate and Connor Hellebuyck (let's assume his regular season form here) behind team captain, then team alternate likely finds themselves in the situation of having to outscore their goaltending problem. I don't think they have enough of a firepower advantage to do that against team captain. That's not to say they don't have a firepower advantage, because they do, I just don't think it would be enough of an advantage.