AFAIK the high quality of the French ships in the eys of British captains and admirals could have been a product of their financial interests. The most lucrative situation for captains and their admuirals was when a captured French ship was taken into British service. Therefore, they praised the quality of their French prises in order to make this happen.
When I understood some dissertations on this topic (from UK and germany) correctly, the maintainance costs of French ships (Men-o-War and Frigates) in British service was much higher than the costs of UK build vessels, which would indicate that Britsh vessels were actually better suited for the missions the RN faced.
Olaf Kunert