Both are nice
From Vila do Conde on the Central route you pass nice places like Barcelos Ponte de Lima. You can stay at Portugal’s best privat albergue
Casa da Fernanda in Vitorino de Piães and climb to the highest point of the entire caminho Português , the Alto de Portela Grande between Ponte de Lima and Rubiães .450 meters above sealevel
From Caminha at the coastal route you have a nice walk along the Atlantic coast, nice towns such as Viana do Castelo and Caminha and a nice walk at the Ecopista path alongside the Minho river
I walked both several times
Hard to choose but if it is your first time I should cut to the central route in Vila do Conde and experience more north Portugal as it is.