Protein bars have wayyyyy too much fat usually, stay away from those as a food supplement eat something real. I've found designer whey mixed with WATER and ice in a blender really helps fill me up, doesn't taste the best but its only 90 calories with almost no fat. On days im not doing anything active i bring nuts and dried fruit, that helps me alot. Lately i've been eating these larabars which are just fruit and nuts and no additives made up into a soft bar, they're pretty good, but not as filling as a bag of almonds and cashews with some dried fruit in it, less fat though.
I generally think people eat too many energy bars when they don't need to be, unless your burning several thousand calories i think energy bars should stay in the cuboard, they're not real food. Too high in sugar and fat usually, they're just candy.