In my experience, the easiest urban outdoor furniture to repair is a modular bench or picnic table with a bolted metal frame and individual wooden or composite slats. If one slat cracks or an armrest gets damaged, you can usually unbolt the bad piece, order or fabricate a matching replacement, and swap it out with basic tools. That’s much simpler than dealing with a fully welded one-piece bench, cast concrete unit, or custom molded chair where the whole thing has to be replaced or hauled off for specialty welding.
The key features to look for are standard hex or security bolts, accessible fasteners, replaceable slats or panels, and a simple powder-coated steel or aluminum frame. Materials like cast aluminum, steel, and standard timber tend to be more serviceable than integrated composite designs with hidden clips or proprietary parts. Bolt-on armrests, legs, and backrests also help, because a damaged component can be removed without touching the rest of the furniture.
If you’re choosing street furniture for a park, plaza, or campus, I’d lean toward a commercial-grade slatted bench with a bolted frame and a small stock of spare slats and hardware. It may not look as seamless as a sculptural custom piece, but it’s far easier to keep in service over time. In short: modular, bolted, standard-hardware urban outdoor furniture is the easiest to repair when a part breaks.