Just try out different bars of most anything. When you find what you prefer that's probably going to be it.
Bananas or other fruit whether fresh or dried works well if you prefer it over gels or other bars.
It's better you eat that Snickers bar while cycling than when sitting around doin nothing. But most anything that has most of it's Calories from carbohydrates is usually ideal. Protein is more important after the ride, but a little while riding certainly won't hurt.
Don't go overboard with electrolytes. If you aren't riding hard for a long distance you probably don't need any. And don't think more is better for electrolytes. Too much is worse than none many times. And most things you eat and even drink has them in it whether they advertise that or not.
While you are worried about nutrition while riding, don't forget to hydrate. And if you want you can put all your Calories in your bottles and not have to worry about eating Calories which to me is sometimes a chore on the bike. Drink something, even just water. A gulp or two every 10 - 15 minutes.