I think you can actually make a fairly educated decision, based on the medical/research literature available on this site, through the ANA, online, etc.
I believe there are, at least, abstracts or summaries available on this site of dozens of articles regarding the relative outcomes of surgery, radiosurgery, etc. Maybe there's even some full length articles? Some of this is available from the ANA home page. Maybe you have to be a member to access this?
That's how I reached my decision - read, read, read the literature. I also thought the ANA patient survey on the home page was invaluable. It was actually one of the primary factors in helping me make my treatment decision.
I'm kind of an over-educated egghead type. Not everyone else is. If you're not the reading/research type, I suggest you get a trusted friend/family member to help you wade through some of this stuff. Very complicted decisions to be made by us ANers, and very dependent on your individual situation (size/location of AN, symptoms, what type of job you have, insurance, what problems you feel like you can tolerate for potentially the rest of your life). Good luck with your journey!