What calorie should I go by?

Over the holidays, I got a heart rate monitor that measure your HR, and calories burned, plus where your resting, and fat burning HR should be. My question is this. Today, the machines at the gym estimated me to have burned 1100 calories between running and the elliptical. But myfitnesspal estimated me at around 850 calories burned. But then my HRM told me I burned 587 calories today. Which one should I go by?