How did the Visegrd Four's integration in the EU differ from other areas?

In post-communist eastern Europe, nationalism, corruption, and reluctance to change to a democratic system significantly differed in the newly independent regions. Hungary, Poland, the Czech Republic, and Slovakia were successful in implementing political reforms and suppressing anti-democratic uprisings. On the contrary, Romania and Bulgaria had more difficulty with corruption, lack of investment, and unorganized planning of the economy. The unification as the Visegrd Four led to a cooperation of internal reforms with an eye towards joining the EU. The factors that worked best for them (and were absent in other areas) were a coherent and cooperative political leadership, public support, and a preexisting infrastructure that made economic and administration transitions possible. The EU and the U.S. saw these four nations as the more advanced of the former communist states, and were willing to invest in them both politically and financially. In other areas mentioned, they were reluctant to allow investment since they were undermined by significant political corruption and autocratic regimes.