Fitbit vs myfitnesspal... Which calories to go by?

It depends. What was the activity and how are you finding out what Fitbit estimated just that activity at? The Fitbit adjustment isn't its estimate of your workout. Nor is the calorie number shown on the device after a workout, unless you set the timer to 'record' the workout separately.

Very good question. For instance I just walked 5 miles on a treadmill. My Jawbone Up, similar to Fitbit shows 610 calories burned, the treadmill monitor shows 475 calories burned, and then when my Up synced with MFP it only gave me 197 in a burn. So to be safe, I always take the lowest. So 5 mikes means a 197 calorie burn.

So 3 different devices, all widely different from each other.