IMHO they are both gorgeous for very different reasons. The Coastal is a bit longer, but not by that much. The coastal does have ups and downs, and may be more strenuous that at first appearance. But the coast is the coast, and we did portions on the Senda Litoral, which were walking on the hard-packed sandy beaches. If you love the beach, this is the ticket!
The Central has way more history, but they both walk on portions of old Roman roads, yet the Central still has more castles, churches, and is the way most pilgrims traveled from times of yore.
They both have sufficient services, accommodations, etc, with the Central having more because of more pilgrims.
If you wish to see my website, with tons of photos, resources, etc to help you make the decision, please click on
day fifteen of the Central Route and
day fifteen of the Coastal to help you decide. Both pages are where I started each section from Porto. I hope you fall in love with Portugal so much that you will decide to both eventually like we did! Happy planning!