I think, it depends on the project you want to realize. The UNA community framework has claimed the greatest possible flexibility for whatever you want to create. When you want to create a twitter-like site then you might prefer hashtagging, when you want to realize a business app, it may be better to chose labels in forms. keywords have a clear meaning and are used for search forms or in relation with search engines in a broader meaning. The flexibility is shown in the fact that you can almost everything turn on, when needed, or turned off, when you don't need the functionality for your project.
I've said it before and I'm just saying that from experience... Users want it simple and not complicated... Nowadays, when there are apps, hardly anyone wants to deal with a page for a long time and only learn how to do it for 1 month system works.
Even an overloaded page where all modules are used ... users will avoid ... because it becomes too confusing ... other sites are showing the way ... Instagram ... only has pictures and streams ... Tumblr is only based on a timeline with profiles... An example is e.g. OK.ru - interestingly, it has a lot of similarities to UNA ... but the site is too overloaded in my opinion.