I only have experience with two.
Lean Mass Matrix is one of the best MRP's nutritionally. I have used the Cinnamon oatmeal flavor. It is pretty thin, which is good if you just want to get it down, and I think it tastes pretty decent. Another thing I really liked about it was that it mixed very well with
cold water in a shaker, so all you needed was a fountain to have your shake.
I am currently getting into a box of Myoplex. It is a whole different animal than the Lean Mass Matrix. It makes a VERY thick shake. I like the taste very much (choco) and enjoy them. 270 cals with the carbs being maltodextrin, so not the best nutritionally. I bought a 42 pack for the value. However, I have found you MUST blend Myoplex. I tried to shake some up in a shaker and the results were pretty disgusting.
When I have some money to spend I plan on buying a box of LMM. I will use LMM when I am at class and on the run, and blend a
Myoplex shake when I am home.