Driving around Spain and Portugal for about 3 weeks. Between arcos and cordoba, One or two nights in arcos? One or two nights in cordoba? Next question , 2 or 3 nights in Porto.
I would spend at least 2 nights in Cordoba. There is a lot to see and do here: The Mezquita, the Alcazar and its beautiful gardens, the Roman Bridge, exploring the Juderia, Palacio de Viana with its 12 patios, etc. The Juderia is so pretty and atmospheric with its narrow lanes, white-washed buildings, flower pots, patios, etc. We spent 2 nights in Cordoba, but an extra night would have been nice for leisurely wandering and getting lost.
If you arrive early enough in Arcos de la Frontera to walk around then one night should be sufficient. The town isn’t very large. Two nights for Córdoba and three nights for Porto, but those are dependent on what you want to see in each place. Time of year, meaning the number of daylight hours, will factor in.
I was thinking 2 nights in cordoba so this helps. Last time in Andalusia 7 years back, one night in Ronda was enough. This time round doing three nights in Sevilla.
Did you visit Sevilla during your last trip to Spain? If not, then I would recommend 4 nights in Sevilla for a first-time visit if you can add an extra night to your trip.