Ubercart vs Drupal commerce for french ecommerce site This is my first experience with french e-commerce site . I want to know which solution will speed up the developing of the website . 

Also is there a module payment for Carte bleu  in drupal commerce, and is it ready for production site ?
Check this article which compares Ubercart &amp; Commerce modules. Winner is commerce module for most advanced features and simplicity.

Commerce module is written from scratch to solve usability and other issues in Ubercart. Commerce module will be obvious choice for E-commerce portal.

As far as i know there is no out of the box module for Carte bleau payment gateway. But, if you know the module development you can write one and contribute to community using commerce payment gateway API. This will help you.

Best of luck :-)