Among the countries you listed, Germany had long-term success with adopting democracy after World War II. The post-war democratic system established in West Germany has proven to be stable and enduring.
Spain transitioned to democracy in the late 20th century following the end of Franco's dictatorship, and while it has generally been successful, it has faced challenges.
France has experienced several changes in government and regimes throughout its history, including periods of democracy and authoritarianism.
Liberia, inspired by the U.S. model, has faced significant challenges and civil conflicts that have hindered its democratic progress.
Thus, while each country has had varying levels of success with democracy, Germany stands out as the one with a stable and successful long-term democratic system rooted in an inspiration from the U.S. Constitution and Bill of Rights.