That's an excellent question that city planners and public works departments debate regularly. Having worked with municipal installations for years, I can share some practical insights.
For urban trash cans facing constant exposure to weather, vandalism, and heavy use, both finishes have merits, but powder coating generally offers better long-term performance in most city environments.
Galvanized steel provides excellent rust protection through a zinc coating that sacrificially protects the underlying steel. It's durable and handles impacts well. However, in coastal cities or areas with road salt, the zinc can degrade over 5-10 years, leading to "white rust" and eventual corrosion. The industrial silver appearance also shows scratches and dents prominently.
Modern powder coating creates a thicker, more flexible barrier that resists chipping and fading. The color options help with civic branding and heat reflection. High-quality polyester or fluoropolymer powders can last 15+ years without significant fading or corrosion, even with frequent cleaning. The main vulnerability is deep scratches that expose bare metal, but proper surface preparation minimizes this risk.
In practice, I've seen powder-coated cans in busy downtown areas maintain their appearance and function 2-3 years longer than galvanized counterparts. The initial cost is higher, but the extended service life often justifies it. For maximum longevity, some manufacturers now combine both: galvanizing for rust prevention plus powder coating for color and additional protection.
For purely functional installations in low-vandalism areas, galvanized works fine. But for most urban settings where appearance and longevity matter, powder coating delivers better value over time.