@Builder,
Le Canard enchaîné, an investigative and satirical weekly, is the most important one, as far as I am concerned. It's owned by some of its writters and founders.
Le Monde, a center-left daily, is owned by a mix of private investors, the
Société des rédacteurs du Monde (a group of journalists), another group of Le Monde workers (printers, secretaries, managers etc.), and the
Société des lecteurs du Monde, a group of faithful readers who subscribed to help the newspaper during hard times in the 80's.
Le Monde's holding owns a variety of other titles, e.g.
Le Monde Diplomatique.
Libération, a leftist daily, used to be co-managed by its journalists and owners -- not anymore.
Charlie Hebdo, a satirical extreme left weekly, is owned by a society of writters. I never read it that much, though... too leftist for me.