Which preposition is used after "popular" ? "Popular with" or "popular for" ?

Normally, popular is used with “with”. However, it can be used with in or among depending on what you want say.

Sweden is popular with blonde girls.
Tolstoy was popular with “War and Peace” and “Anna Karenina”.

Baseball is popular in not only USA but also in Japan.
Strategy games are popular among teens.

The word of popular is an adjective and generally used with the preposition “with”.
Popular is also used with “among”.

Istanbul is popular with Hagia Sophia and Blue Mosque.
This policy is popular among the workers.

Popular is used with “with”, “among” and “in”. The meaning changes with the sentence.

Youtube is not popular among the people North Korea.
Venezuela is a country popular with petrolleum.