20 brands with the most loyal customers

Although companies spend billions each year to try to make their brands resonate with consumers, few ever end up with truly fanatic customers.

But the perks are huge for those who do. Loyal customers consistently come back to buy more, they're more willing to stay despite increases in price and they become strong advocates for the brand in their own social circles and online.

Through a combination of psychological assessments and statistical analyses of customers, Brand Keys - a research firm devoted to consumer behaviour metrics - determines how much brands exceed what consumers expect, and how loyal they will be down the road.