Why would you choose a push mower over a gas or electric-driven model? Besides providing a better workout, they're easier to maintain, and easier to store. And in the case of designer Joe McWha's Little Mow, they can actually look more like a piece of modern art than just a lawn care tool.
As fun as it is to cut your lawn with a riding mower, they can be expensive to operate and maintain. Even the push variety end up costing you in the manual labor department, so you might want to consider putting a team of animals to the task.
Growing up, I hated mowing the lawn. My backyard was huge, my allergies were bad and I was stuck with a temperamental push mower. If I had this battery-powered Husqvarna mower, however, I would have begged to do yard work.