The leading brands for Kindle Fire HD cases are Amazon, Belkin, Marware and OttherBox. Any case that you might choose that is made by one of these manufacturers grantees a you high.
When you are looking for the best case for your needs you should consider few impotent aspects that might help you the best case.
First you should choose the case by its protective features and by your need of protection level. If, for example, you use your case in a construction site or some other place that can be dangerous for your kindle device the best case for you is the OtterBox Defender Series, This case provides the highest protection level possible.
If you are looking for a case that is a little bit more stylish and protection is not necessary your first priority you might want the check out the Standing Leather Case by amazon. This case looks amazing and fits perfectly the Kindle Fire HD 7.9 Inch device.
More information: Kindle Fire Or iPad?, Best Kindle Fire HD Cases