It is a personal preference, I have never liked fiber products. So it depends whose views you want to follow. To me Oxypowder is healthier, it brings oxygen in the intestines. I am sure P&B is cheaper.
I follow Andreas Moritz and for a cleanse he feels that colosan, Oxypowder are the way to go instead of a lot of fiber products with herbal laxatives.
So keep reading and do what you are comfortable with. Noone can make the decision for you.
Here is a good thread about colon health. You should read the whole thread. You can also read the FAQ at the top of this page. //www.curezone.org/forums/m.asp?f=337&i=12699