ON whey is very good no doubt about it.
It has a great blend of proteins for PWO... but as said above, MyProtein whey is far better value.
Are your results significant enough between MyProtein whey and ON whey, could you justify the extra cost of ON whey results wise?
I don't think I will see a differance, if there is one I would bet it would be very small.
My desision is for cost reasons only, if both were the same price I would have ON whey because of the blend.
But MP whey is far cheaper hence why I am changing to MP WPC80.