Do people prefer to join groups over customized feed?

Is there any study or experience (personal/professional) related to usage of group versus personalized feed?

Problem statement: I am creating a website where user can communicate on certain criteria, now is it better to ask user to join groups or shall I make a feed system like facebook?

Advantage of group for my project:

• User can chose group with their preferred demographic location.
• User can communicate to the people who have same interest.

Dis-advantage of group for my project:

• User will not be aware about the rest of the interesting topics happening on other part of the world. Ex.: Politics
• Since these groups will be user created so limit of reaching similar interest people will be limited.

Advantage of feed system:

• Open to the world and easily accessible to other users.
• All content on one page, user can post whatever they want and don't have to be lead by some moderator

Dis-Advantage of feed system:

• Not controlled, not easy to aggregate. User have to search for every topic (ex.: Some random political event in Japan)

Few social networking sites which I have analyzed: (problem mentioned in bracket)

• Facebook -> both feed and group (user have friends for personal feed, public group content also visible on feed)
• Twitter -> Feed system (hastag system which makes other users to hastag every important term)
• Quora -> Feed system (UN-organuzied and repetitive stuff, good for general question and answers where you don't want to be a part of community)

My objective:

I want user to meet people, collaborate and share ideas/thoughts. They should be easily connected to people from same geography but can share their thoughts worldwide. I don't want my users to hastag or tag their content.