Finally would the landing charges from DTVA not be a lot lower than from NCL? This may finally clinch the deal.
Difference in landing fees will never be a significant factor in attracting new routes/operators at either NE airport. If an airport wants a route/airline bad enough (or to keep an existing one) they'll give the landing fees for almost nothing, there are other more significant costs involved. And in my opinion the best prices that both airports can offer will be almost identical (i think RYR Girona flights confirms this).