I believe the choice vs powerlessness debate is sort of a false dichotomy. I don't think it's just one or the other, I think addiction is a complicated issue with a lot of middle ground for all the various theories and ideas on why it happens to some people. Trying to settle on one theory will probably take away from the fact that it is complicated, and not everybody uses for the same reasons, some people don't seem to have any reasons at all, it just happens. Yes AA talks about powerlessness in the steps, but if they meant you are completely powerless over your entire life, then wouldn't everybody go drink every time they passed a bar on the street, or the next time a drug dealer asked if they wanted to buy something?
People in recovery make the choice not to use again every single day, and every time they choose to walk into an AA meeting. I feel like it starts out as a choice, but quickly descends after that into an addiction which is more complicated than making a simple rational choice. If people really believed they were completely powerless over their addiction, then there would be no hope of recovery, and no point in going to AA. Relapse is a part of recovery from any addiction, but it's not a reason to give up. You always have to keep trying, even if you slip up.