I HAVE to intake protein daily through some form of supplement since my surgery. This is for the rest of my life. As others have noted - stay away from the majority of protein bars - sugar coated junk marketed as health food. I asked this same question you are a little over 2 1/2 years ago - got the same answers - but found out for myself anyway.
If you must - I suggest you use a company such as this one (I used them, great service and products):
Bariatric Advantage
My suggestion to you would be to find a high quality protein shake that you like. I prefer ON Whey in the double chocolate mixed with low fat (2%) milk. I normally buy the large tubs - but also buy pre-mixed if I know I need to carry with me. The stuff mixes quickly with just a shaker cup - no blender needed.
And lastly - instead of looking to the protein bars to substitute for your breakfast and lunch - look to change your menu, what you are eating. You will do much better simply by changing the diet, go to more smaller meals each day and feel fuller longer. Better for your health.
Good luck!
Ron