There is a site which lists some of the Oneness Pentecostal organizations,
http://www.apostolic-churches.com/organizations.html
You could check some of those out.
If your church is incorporated according to state and local requirements, you can ordain etc. and would not need another organization for that type of legal status. You might want to remain independent with the local church sovereign and not subject to outside control.
As far as joining another organization, who do you know around you and what organization(s) are they in? You might want to join an organization that some around you are in.
AMF, from what I understands, leaves the local churches sovereign. However, the "standards" preached and practiced are quite conservative and you and your congregation may not feel comfortable.
Global Network includes trinitarians and you may not feel comfortable with that.
Church of Jesus Christ in Kingsport, TN insists on KJV only and does not allow the title of "Rev." Those may be issues with you. Also, it's a pretty small organization. (small organization is based on the churches listed on their website. they may have lots of more churches than that)
ALJC is pretty moderate and has churches lots of places. You may want to consider them if there are churches and ministers in your area.
UACoJC is small (about 18 churches, I think) and mostly in Indiana but it seems to be moderate to conservative from what I understand.
PAW is pretty liberal. That may be a problem for you.
I really don't know much about other groups.