Popular stainless steel is durable & easy to clean. When you see 18/10, "18" is chromium; the 2nd number is nickel, providing a shiny, rust-resistant finish. Higher is better.
Lightweight, inexpensive & an excellent heat conductor. The key to aluminum cookware is thickness. A downside is it can react with acidic/alkaline foods to corrode the material.
Hard-anodized cookware is twice as hard as stainless steel, has the heat conductivity of aluminum & has a non-stick surface. It's best to hand wash your Hard-Anodized cookware.
Other cookset materials include Copper, Cast Iron, Enamel on Steel and Glass cookware, each with its own price tag, benefits and detriments.