Oporto Rental Management should be your go-to choice if you decide to stay in Porto. it is by the river (which it so beautiful at night for the view of Gaia and everything around it) and it's easy to go anywhere. the apartment is spacious and very clean. the view from the balcony is also beautiful. they have a chalkboard wall in the apartment with their wifi information as well as greetings from past Airbnb guests. so you get to make your mark on their walls (literally)!