If you're concerned about maintenance, you're asking the right question! The bench material you choose dramatically impacts how much time and money you'll spend on upkeep. For the absolute least maintenance, focus on modern metal and concrete benches.
Powder-coated aluminum or steel benches are top contenders. The powder-coat finish is fused to the metal, creating a shield against rust, UV rays, and moisture. They rarely need more than an occasional rinse with a hose. Avoid cheap, painted metal, as the finish will chip and rust.
Pre-cast concrete benches are virtually indestructible. They won't rot, rust, or become damaged by insects. Their heaviness is a stability bonus. While they can develop a natural patina over time, they require zero proactive maintenance. Modern designs offer more style than the bulky slabs of the past.
For a warmer look, consider high-quality synthetic lumber (polyethylene or composite). While not entirely maintenance-free, it resists splintering, rotting, and insect damage far better than real wood and doesn't require annual staining or sealing.
Benches to *avoid* if you hate upkeep are untreated natural wood (like pine), which rots quickly, and wrought iron without a durable finish, which requires regular painting to prevent rust. By investing in metal, concrete, or high-grade synthetic materials, you can enjoy your outdoor seating for years with little to no work.