FitBit Versus Polar HRM... Which Is Better?

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Howdy, fine people of MFP land. I've been wanting to get an HRM and have been researching prices and brands, but still can't make up my mind. Is there anyone out there who has had experience with both a FitBit and an HRM (Polar was the brand I was looking at)? If so, which did you prefer? Do they both basically do the same thing? Is a FitBit accurate in the calorie burning range since it does not have a chest strap?

So many questions, so little time. Basically... is a FitBit worth the price? Any advice would be the awesomest!