You already have a blog if you run WordPress.
Depending of how many authors you expect, and money you have, you can opt for MS and allow a complete blog (like the main blog) to each user. But a blogging farm is a BIG project who need space and powerfull server ressource. BuddyPress is tailored for that. But are you tailored to assume ? 😉
A good compromise for small and middle project is BuddyPress Groupblog wich comes with P2, an extra front-end editor theme. So you have two answer in one plugin.
BuddyPress handles essentially members. Publishing is WP’s job and giving users a possibility of front-end publishing instead of back-end is an endless pros and contras discussion. And in any case, a long front-end dev work. At least.
How would MS work with Buddypress, does it integrate well with the buddypress profile page, will the users blog posts show up on the profile page. I heard a plugin called Gravity Forms can achieve this as well and a plugin called WP User Front-end.
MS integrates wonderfully with BuddyPress. When network activated on a Multisite, activity from across the network is recorded on the users Profile. Just be sure to check Site Tracking under Settings/Buddypress once you network activate BuddyPress (https://cloudup.com/i_-p1kJGUwd). Once upon a time, BP was ONLY compatible with Multisite: you couldn’t run it on a single WP install.
Note that this will give your users the ability to have their own blogs. This is separate from the ability to post from the front end. For this you would need to make a theme like P2 your network default. http://premium.wpmudev.org/blog/how-to-set-the-default-theme-for-wordpress-multisite/
Thanks for all your help. I don’t think I would need multisite at the moment, maybe when my site grows to have more dedicated bloggers. Can you give me your opinion on a plugin called Buddyforms http://themekraft.com/store/wordpress-front-end-editor-and-form-builder-buddyforms/
It looks better than BuddyBlog
Thanks once again