Maggie,
Hubby and I are currently enjoying a rest day in Oviedo after walking the first 7 days of the Northern route. Last year we did the Portuguese route from Porto and the year before we did the first 3rd and last 3rd of the French route.
If you plan on doing the Portuguese you may want to consider skipping some places between Porto and Tui as it was Not fun being right on the road next to zooming vehicles. After Tui it was very nice though!
This northern route has been the most difficult of all with the first 5-6 days constantly going up and down. Very beautiful walking so it’s definitely worth the effort. Due to time we have to jump ahead but totally enjoyed the journey this time too!! If you’re looking for more scenery I would say the northern route for sure. Yesterday as we were going from Guemes to Santander the walking was RIGHT on the coast and even on the beach. An absolute amazing walk....even in the misty light rain!
Enjoy whichever you decide!