For the classic Porto panorama, go to Gaia; for a quieter pause, choose one of the city gardens. The trick is not to collect viewpoints but to pick the one that fits the weather, your legs and the time of day.
The bridge view: Jardim do Morro and Serra do Pilar
Cross the upper deck of Dom Luís I Bridge to Jardim do Morro for the familiar view over Ribeira and the river. At sunset it is busy; if you want space to look rather than queue for a photo, go earlier. Walk a little farther uphill to Serra do Pilar for a higher angle and a quieter place to stand. The slope back down is steep, so don’t wear shoes with no grip.
Central Porto: Vitória or Clérigos
Miradouro da Vitória is a rough-edged stop above the old centre. It gives you roofs, river and bridge without a ticket, but the ground is uneven. Clérigos Tower is the paid, stair-climbing option: go when the sky is clear and check the current visiting information before setting out.
For a bench and room to breathe
Jardins do Palácio de Cristal are my pick when I want a view with somewhere to sit. Paths, peacocks and the Douro make this more of a slow hour than a dramatic photo stop. In Foz, start at Jardim do Passeio Alegre and walk toward the Atlantic if the weather is decent; the wind can change the plan quickly.
If you have one evening, do Vitória in daylight and cross to Jardim do Morro later only if you still want the sunset crowd. Keep Clérigos, Palácio de Cristal and Foz for another day. Porto’s hills make “nearby” a poor measure of effort.