I bought Social Engine and I was impressed with the overall performance. It has some awesome plugins.
Elgg is not a bad alternative either.
What I like about UNA, is the immediate accessibility and ease after the learning curve. But then all the problems start. If you want special features as a non-coder, you're in trouble. UNA is not very well documented, when opening the files. There is no coding roadmap. Geekgirl explained why this is and that worried me because it means that the current team, doesn't really know what is inside of UNA. We are fumbling in the dark. Also both Elgg and SocialEngine were very quick to make mobile apps. UNA is still developing. To me it seems that the UNA team is spreading too much over too many areas, instead of making a focus and finish it. My concern is the survival of UNA, because in many areas, UNA is way behind the others. Quality is a concern. Security is a concern.