I like the trail mix that my wife brings home once in a while. Usually has a bit of granola, pieces of date, sunflower seeds, almonds, dried banana, chocolate covered raisins and lots of other things.
I like Fig bars and they'll come with me once in awhile.
When I have it, I'll go to the trail food my ancestors carried and grind up some buffalo jerky and add it to parched corn that's ground into a coarse flour. It's an excellent trail food if eaten sparingly. A couple of tablespoons full and chased with drink, swells in the belly and fills me up. Any more than that and I experience discomfort like I ate a whole hog by myself. Energy, nutrients and burns clean with no ill effects if I have to live off of it for a month or more.
I also like taking honey with me. The list of medicinal benefits are extensive, plus it's pure energy and burns efficiently without ill effects for most people. However, raw honey does contain botulism spores and shouldn't be eaten by very young children (infants/toddlers) or those with a weakened immune system. If for no other reason, I think the fact that bacteria can't exist in honey at all, makes it worth packing along.
I used to carry the so called power bars, but when compared to the more natural methods of obtaining energy they aren't worth the expense or ill health effects they offer.