Okay, you need to build a social network app and you aren't able to figure out the right tool to do the job. You got two options :
If you follow the 1st approach Elgg is probably a great choice. In case you want to build one from scratch you need to zero down on a tech stack. You can't achieve it with just Laravel or Foundation App. You need to use a combination of technologies to do the job. Looking at your poll options I assume you are comfortable with PHP. So, you can actually use PHP+Laravel as your middleware. Then you need to choose a database which can be MySQL, MongoDB, Neo4j or some other DB (you need to spend time to figure out which one is the best for your app). On the front end you can use foundation for apps or a JavaScript framework like AngularJS, Meteor etc. So, all in all you should look at various tech stacks and DBs and front end frameworks to see which one works for you.
So, the tl;dr is that if you want to get started right away without much coding you should probably be fine with Elgg. But keep in mind that you may not get complete freedom with it. On the other hand, you can custom code an engine for yourself which takes time, but gives you great freedom.
Personally, I would choose the 2nd option.