A perfect snack is to have a fruit (or fruit portion) with nuts/seeds (butter): so that you can enjoy the sweetness, nutrients and fibres of the fruit without having a sugar hike and crash because of the fat of the nuts/seeds.
Fruits. Best fruits are the berries because of their low GI/GL (Glycemic Index/Glycemic Load) content: strawberries, raspberries, blueberries, blackberries. But other fruits are great too because they offer a variety of vitamins, minerals and nutrients. Always make sure not to have more than twice the same fruit per week.
Nuts and nut butters: almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecan nuts, peanuts, pine nuts, pistachios, walnuts. Have them raw as much as possible. Roasted and salted ones are not as healthy.
Seeds and seed butters: pumpkin seeds, sunflower seeds.
Because the magic happens in the kitchen!