I don't log calories, because I learned that I'd have the tendency to be over obsessive about every. SINGLE. calorie. I do, however track my sugar intake, since that is my method of choice. For that, I kind of mentally do the math (it's so much easier to count up to 15g of sugar max rather than tracking 1400-1500 cals or whatever), but I do also use MFP and the like if I'm unsure on sugar count and have no access to nutrition info (if I'm eating out).
Good luck with the choice you ultimately decide to make!