Coquitlam: widest selection, three SkyTrain stations, largest inventory across all price bands.
Port Moody: smaller, arts-and-brewery identity, higher price-per-square-foot, better core walkability, shorter commute to downtown via the Inlet.
Port Coquitlam: roughly $100–200K cheaper on equivalent property, more detached home for the money, fewer transit options, more suburban feel.
The decision is selection vs lifestyle vs value. None is "better" universally — it depends on which trade-off matters most to your move.