The group of dispensaries that are responsible for persuading MPP to eliminate personal grow rights are the dispensaries that are members of the "Arizona Dispensary Association", which is run by Andrew Myers.
Andrew was hired by MPP back in 2009 to be the Campaign Manager for Prop 203. He now has a dispensary in Scottsdale named "Monarch Wellness."
His organization, the "Arizona Dispensary Association" (ADA), represents numerous other large State-Licensed dispensaries. It's this group of large dispensaries that represent the greatest influence with MPP.
There are likely other dispensaries not affiliated with the ADA that are also against personal grow rights, but they don't have as much weight with MPP, for obvious reasons.
A few of the dispensaries have come out publicly to say that they DO support personal grow rights. Those dispensaries should be praised for standing up for whats right.
It's difficult to give you a list of which dispensaries are members of the ADA, primarily because many of the dispensaries are lying and telling the public that they aren't ADA members, when they really are.
The guys at Safer Arizona interviewed Andrew Myers and asked him why the decision was made to eliminate personal cultivation. His answer was that the "law enforcement types were very against personal cultivation and that it was necessary to get their support."
You can read the whole interview
here