Schluter... Membrane over green drywall?
The answer on what will be easier depends on how square and flat the walls are currently. If the walls are already really flat(no more than 1/16&quot; deviation in 2 ft) and the corners are square then you proceed with the membrane. If there is any work that needs to be done it is easier to shim the studs and/or plane studs before wall install. Take a level to the wall and check it everywhere.