I am having the same issue. OpenStreetMaps is just poor. It doesn't recognize many street addresses and zip/postal codes. That's why it's free. It is maintained and updated by volunteers. A lot of information is either missing or outdated. This is a serious issue for a community-based website. It will also be frustrating for many members when they will see their address not being recognized by the UNA site. 

So far, Google Map is the best out there but it can get way too expensive.

I am kinda lost too. I am looking forward to another Map integration that really works!