Circle vs Mighty Networks: Which is best for you?

It has great community building tools, with different formats for different content types, the ability to organize folks into different spaces and groups by topics or persona, and a very well built out event hosting capability.

I feel the site still lacks a lot of customization features.

I just wish that upon rsvp'ing to attend an event, that it could be AUTOMATICALLY added to my calendar.

Our organization is very low on revenue right now (these are hard times all around!) and Mighty Networks refuses to refund the $275 charge that just hit our account for an annual subscription that we will not use.