Peanut M&Ms. Or the almond ones if they have them. Mostly because I enjoy them.
Any sugar that goes into your body is getting burned off. That's a good thing. You need energy, it's what moves your bike and gets you home. Sugar is quick energy. Even better if you can find something with fructose too.
+1 on refill your bottles and ice. I'll carry some electrolyte tabs if it's going to be a long ride and I'll have this option.