Basically, there's a three-part litmus test that you can apply to any kind of snack food. I think it's helpful.
1. Will It Fill You Up? The key words here are and protein and fiber. These will keep your energy levels on an even keel and give you that long supply of energy, rather than quick burst. Ideally, you want around 10 grams of protein and six to 10 grams of fiber in your snacks.
2. Is It Minimally Processed? My big go-tos - whether I'm choosing snacks on my own or making recommendations - are nuts and seeds (like what you'd find in a trail mix). They're nutrient-dense and filled with healthy fats (which will also help keep you satiated). But even if you don't feel like reaching for some almonds, going with foods that haven't been processed to death is definitely the way to go. As soon as processing gets involved, then as a result of the heating or the human intervention, it tends to deplete the nutrients because vitamins and nutrients are very fragile. That's why raw foods are really great because all the nutrients that naturally appear in the food still remain in there.
3. Do You Actually Like It? Snacking isn't just about filling up on veggies and other whole foods. Enjoyment is a huge thing when it comes to snacking. You don't have to rely on willpower to keep yourself from eating the foods you really love if you're already eating foods you really love (albeit nutritious ones).
...But What About Calorie Counts? I'd say forget about them. That's because you're not looking at calories as the barometer for health. You could have 200 calories of white chocolate or something that doesn't contain any nutrients whatsoever and compare that to 200 calories of coconut. In the body, it's going to have a totally different role and effect. Instead, I'd say just go off of your hunger and fullness cues. The likelihood of your overeating is low if you eat mindfully and have foods full of nutrition.