Honestly, there isn’t one perfect material for every city, but if rust prevention is the main concern, I’d choose powder-coated marine-grade aluminum for most urban trash cans. Aluminum doesn’t rust the way steel does; it forms a protective oxide layer, and a good powder coating adds another barrier against scratches, salt, and cleaning chemicals. It’s also lighter than steel, which makes installation and emptying easier.
For high-traffic or coastal locations, 316 stainless steel is the premium option. It is stronger and very corrosion-resistant, but it costs more and can still show rust if cheap fasteners or road salt sit on it. If the budget is tight and the bins are not exposed to fire or heavy vandalism, HDPE plastic is the only truly “never rusts” choice, though it can fade, crack under abuse, and melt.
I’d avoid ordinary mild steel, even galvanized or powder-coated, because once the coating chips, rust starts fast. For a practical city standard, powder-coated aluminum gives the best balance of rust resistance, durability, appearance, and maintenance. In coastal cities or places where looks matter, go 316 stainless with stainless fasteners. In parks or low-risk areas, HDPE can work well. So my short answer: marine-grade aluminum for most cities; 316 stainless if you can afford it; HDPE for budget no-rust bins.