I would recommend Lagos over Salema.
We spent almost a week in Lagos in April 2019 on a retirement scouting trip. We did plenty of exploring around the city, walking along the cliffs, exploring Luz, visiting an organic farm, a winery tour, eating, drinking and soaking up the vibes. Never got bored.
We also spent 3 days in Lisbon walking, eating, and exploring.
My husband loved Lagos, my mom and I adored Lisbon. Sadly, we did not make the stretch to purchase a home in either since we each already had two homes(snowbirds) and did not want the hassle of selling our winter places to buy in Portugal. Oops!