Not sure how much help this will be, but just adding my own experience with the two. I've had a Churchill with quite a few years age on it and the only Lucis I've had were from 04. The aged Churchill had the most incredible toasted tobacco taste. It just seemed to gain strength as it smoked without ever being harsh. The Luci was the usual Party taste that was milder in comparision as well as a more muted taste.
So I guess, being Mr.Obvious here, I'd go with the one that I could get with the most age on it. If you were looking to age them yourself, then the Lusitanias would probably be the better of the two in the end.
Gary