Benchmarked strictly across TripTiming's 5 empirical pillars: Crowds, Weather, Vibes, Prices, and Safety.
Porto emerges as the optimal December destination with an overall TripTiming Index of 68/100 vs 67/100 for Lisbon (+1 point advantage). Porto experiences substantially lower visitor footfall and shorter landmark queues (low density / tranquil vs moderate footfall in Lisbon). This is reinforced by lower lodging rates (~$140/night vs ~$177/night, saving ~$259 over 7 nights). While Lisbon retains an edge in Weather Comfort (79/100 vs 64/100), Porto's commanding performance in Space & Crowds secures the overall December recommendation.