sparkpeople tracking is WAY smoother than fitday in my opinion... plus, for brand-name products often someone else has already entered the info (oh just noticed you said "form other users").
BUT sparkpeople is full of CW and totally obnoxious in that way... fitday is "cleaner" of that crap.
Then again, sparkpeople lets you stay logged in and fitday always kicks me out so i have to re-log-in all the time. Which is annoying.
But I deleted my SP account when I got fed up with the CW. Luckily I rarely track/import foods anymore so fitday works when I do out of curiosity.
Eating lots but still hungry? Eat more fat. Mid-day sluggishness? Eat more fat. Feeling depressed or irritable? Eat more fat. People think you've developed an eating disorder? Eat more fat... in front of them.