The best higher education institutions in France are the "Grande Écoles", which are very small compared to North American univesities. Around 500 students graduate each year from the École polytechnique, for example. Although there are a lot more students who study to be accepted at these écoles, they do so in another parallel system called "classes préparatoires". Which is in its self separate from French university system.
The French language does play another important role. France has not adopted english as much as Germany or the Scandinavian countries have. Publication is almost always done in French. Although my American friends tell me things have improved a lot in the past 10 years.
Finally, although french universities and grand écoles perform basic and applied research, a majority of the work is done at public research labs. Their scientific results are attached to the lab, which are not part of the universities. Although they can often be in the same location.
Nonetheless, if you ever have the opportunity and get accepted by one of these écoles do not hesitate to go. They are very good schools.