The super-slim successor to the K10/K15, the Keurig K-Mini is just 4.5" wide and brews 6-10 oz with its "fill before each use" reservoir. If you want fancy features, look elsewhere. If you want compact coffee, look here.
Keurig's first machine designed to brew lattes and cappuccinos, the Rivo has since been discontinued and replaced by the Keurig K-Cafe and K-Latte. We'd go with one of those, but you can still find the Rivo online.
The crown jewel of the Keurig 2.0 pod-scanning system, feature-rich K500 series brewers offer 11 brew sizes (up to 30 oz) and massive 80 oz reservoir. Now discontinued, we recommend the Keurig K-Duo Plus instead.