Dyson DC59 Animal

It's expensive and quite loud (90 decibels), but the DC59 sucks the hardest and, unless you've got wide expanses of carpeting, could credibly replace your primary unit (especially when using the included wand attachment). The motorized head eradicated all dirt and even left clear tracks on a floor covered in baking soda – a test that required other models to make multiple passes. And it was the only unit that showed no leaks. [$500; dyson.com]