Robin.....
The DR400 is a masterpiece and is the mainstay of most French flying clubs so parts are normally not a problem.
The metal Robins are average aircraft and are unusual in French flying clubs
It won't take a rocket scientist to figure out were Robins parts supply is directed.
The truth is that Cessna parts are a little better than Robin parts for availability but the Robin parts are usually cheaper.
When it comes to structure the DR400 is much cheaper, you just go to an aviation wood merchant .