It's funny this should come up, because I had to use fitday today. I usually use this site
http://www.calorie-count.com/, but it's doing mainenance or something today, and I couldn't get on. )This is the first time I have ever had this situation with this site)
Anyway, I like the calorie count site better, because it has a lot more foods already in the date base. At least, it's easy for me to find what I eat. They already have lots of 'healthy choice', 'lean cuisine', as well as foods from most of the food chains. So it's very easy to tally things up, because it's already there, and you don't have to track down a label.
I think it's just a personal choice, and what you get used to. Calorie count also analyzes your diet and 'grades' you. Although, I don't know how accurate it all is. As well as a food log, there is an activity log.
I just thought I'd throw that out there as an option to 'fitday'.