From my experience, I worked for a project-base company before, project-base company is easy to work with, but sometimes sometimes closing a project can mean losing your job or wait for next project which loosing time and money. In project-based organization the whole team is focused on the team’s goals.
I prefer to work for a Matrix-organization, you can work on lots of different things, getting more experience. You have to work with two bosses. In a matrix-organization give faster decentralized decisions.