I just switched over to myfitnesspal from sparks mainly because the database of food is better. However, the one caveat that I would say for all of the sites is just to ignore what they think your goal calories should be. IMHO, everyone has to determine what calorie level works best for them. All of the sites offer good means of tracking your calorie and carb (for people like me who need to track both) for the day. Just depends on which you like better for the "extras."
Mini Goals: Move Here Weight (2005): 344 (Done), Stop Smoking Weight (1997): 333, Mom Remarried (1990) 313, Twoderville: 299, Move to NC (1989): 280, Closer to 200 than 300: 249, More to Come....