I like using Fitbit.com (and wearing the Fitbit device on my bra, about $100, but no monthly cost after that purchase), because it takes into account how active I am and motivates me to be more active in small ways that add up. It tells me exactly how many calories I can eat.
This works well for me, because some days I am more sedentary than I'd like
and other days I walk 6 miles or even run a half marathon.
So the calories I need can vary wildly.