We spent a month at Miguel's place.
It is super clean and is located right in the centre of Porto - you can walk to almost all the sights and for the more distant ones you have the metro less than 5 minutes away.
Miguel is a great host - there was fresh fruit and cute little bottle of port in the apartment. He is also easy to reach if you require anything.
One minor annoyance - there was noisy construction happening on the other side of the wall every day from 8.30. Hopefully this ends soon (or has ended already - this was in Jan-Feb 2019).
All in all this is fantastic value.