Consumer Reports says treadmills are a great choice to help with weight loss. Consumer Reports named the Proform Pro 2000 a Best Buy for around $1,200. It folds and is easy to store.
If you're just starting out or you have back, hip or knee problems an elliptical is a great alternative to a treadmill. It creates less impact on your joints and can still give you a great cardio workout. Consumer Reports says AFG 3.1AE for $1,100 is a great choice.
Spin bikes provide a good interval workout Consumer Reports recommends the Diamondback 510ic for $800. It has a built in work-out program that keeps you moving.
Another option is a rowing machine. Rowing machines provide a full body workout for both upper and lower body. It's non-weight bearing but it's still very strenuous so it can burn a lot of calories. You do want to make sure it fits. The $900 Concept2 Model D proved comfortable for both short and tall people.