Do you think it is preferable to use whey or casein for this recipe of homemade protein bars?

3 Cups Oatmeal
1/2 Cup Natural Peanut butter
1 cup Skim Milk
4 Scoops Protein Powder
dash of cinnamon

11g fat (good monounsaturated fats)
26g carbs
21g protein
285 calories

I would consume one of these bars while at work or school. What do you think?

A mix would be good, but if I had to pick it'd be casein.

Casein is considered a slow protein with regard to absorption and coagulates in the stomach.

Perhaps you can look at this whey vs casein

Step #1: Consume a whey protein drink shortly after a whole food meal.
.....

Step #2: Consume casein based meal with in the next 3 hours.
.....

Step #3 Repeat! That’s all there is to it.
.....