The easiest shower to install is typically a prefabricated shower kit. These kits come in a variety of sizes and styles and can be purchased at most home improvement stores. They include all necessary components, such as the shower pan, walls, and hardware, and can be installed by a homeowner with basic plumbing skills and tools. The installation process usually involves connecting the shower drain, securing the walls to the framing, and installing the showerhead and controls. Overall, prefabricated shower kits offer a convenient and straightforward option for DIY shower installation.