It really depends on what you are using your protein for and when you take it. I have found that certain proteins work best for certain needs as well as certain times during the day (or night). Is there any specific type of protein you are looking for?
I have found that like X mentioned, I only change flavors now because I have a definent set of 3 'different' types of protein blends I use depending on my needs at the time. So I differ for taste reasons... besides, you don't want to taste chocolate for the rest of your life right? :cool: