Multisite setup now what Plugins do I need?

I have manually installed the network multisite. Now I am looking for advice on what are the best plugins for me to get, based on the following. I want a user to be able to sign up from my site and they can easily create a page, and then their friends can add comments. I am also interested in monetizing, but not sure if it is better to go with paid membership, free with ads, or a combo?

Thanks in advance, if you can help.