If you get the opportunity to stay at Maria and Fred's AirBnB, please do! It's a beautiful apartment that was clean, spacious and in a perfect location for walking around Porto. The view is spectacular from both the balcony and garden, and we loved spending time here. Maria and Fred were extremely welcoming and let us drop our bags off before the check-in time and also booked a lunch and dinner reservation at great restaurants on our first day in Porto. When we accidentally left our keys in the apartment in the morning, Maria responded right away and let us back in :).
I hope I get the opportunity to come back here and I am definitely planning on recommending it to my family/friends.