Most robot vacuums look exactly the same. They're monochromatic discs that wander around the floor, bumping into your side table, doing their best to pick up crumbs, pet hair, and flecks of dried mud. But despite their similar appearances, there are important differences that dictate which model is best for your abode. You have to consider battery life, the size of the trash compartment, bonus "smart" features, and—of course—price. Since I’ve gotten to see some of these suckers in action over the last few months, I thought I’d write up some of my favorites.