If you're like most people, your primary factor is taste. It doesn't matter how nutritious a food supposedly is if it doesn't taste good to you.
Our cravings for food changes based on a variety of factors. Different foods sound good in different circumstances. Sometimes it's based on what your body needs – e.g. if your blood sugar is getting low you will probably crave carbohydrates. Other times it's circumstantial – e.g. a hotdog sounds good at the ballpark.
Sometimes just seeing or smelling a food makes us want it (hint: this is how food marketing works). Imagine that you walk into the mall and smell fresh baked cookies. Suddenly you want one from the bakery.
For those with eating disorders, they are fighting against their body's natural desires with food choices. Instead of listening to the body they listen to the ED voice in their head telling them what they should or shouldn't eat. And eating a forbidden food is punishable. The only way to maintain virtue is by obeying the ED.
Rediscovering normal eating is a process of reconnecting with the body and it's cravings for food and learning to make food decisions based on body signals rather than ED rules. This can be scary if there's ongoing mistrust of the body, but the body truly does know best.