Is it better to have less fat or less sugar?

Common sense: It's best to restrict your total calories to what you can use daily without becoming or remaining fat. There's so much mumbo-jumbo and different advice here that i'd urge you simply to eat what seems best to you, trying to avoid very sugary, very salty, and very greasy stuff, and to stay physically fit. Worrying yourself over "pop" advice makes life even more difficult.