Tendenci. Happy but with some caveats
Due to the type of organization we are it is part of our mandate to use FOSS (Free Open Source Software) whenever possible. During our initial search this quickly limited our choices and we decided to on Tendenci.
Because we are using the Open Source version, this means that we self host and maintain the software. This review only covers the Open Source version, not the hosted version from Tendenci.
The software itself is straightforward and easy enough to use. We've found it reliable and free from major bugs and issues.
My only complaint is that customization to meet our particular unique needs has been very painful, While we are very tech savvy we are not Python/Django developers and we've found it very difficult to find and engage developers for customization. Tendenci was also not helpful, and while we interfaced with several people at the company found them difficult to engage, with them preferring to push the "hosted" version.