All the organizations have their pluses and minuses. But two points - one being designations. IN 12 years I have yet to be asked if I have a designation except about 5 times and EVERY one asked about an MAI. So from my perspective anything but an MAI is a waste of money. It is also enormously expensive in time and money.
Speaking of which....most organizations charge too much, perhaps because they are too small, spend too much on fruitless lobbying, and several organizations have went from financially sound to S & L status. A single organization would go along way to help, but many small professional organizations do not charge as much as NAIFA, ASA, ASFMRA, or AI for membership. In my state even lawyers and CPAs pay much less to belong. I am a member of the Amer. Assoc. of Petroleum Geologists. AAPG charges $110/yr. $75 more for a designated title, $35 or so gets you into either the division of energy minerals or environmental earth sciences which has quarterly reports and publications as well. Monthly magazine and monthly Journal, good educational offerings, trips, regional meetings, etc. etc. How can they do it at this price with a few thousand P. Geo's and it seems almost every appraisal organization is on the brink of bankruptcy?