Let's examine the usage of prepositions in each option:
Option (1): "I prefer coffee over tea." — This sentence correctly uses the preposition "over" to compare two things, which is standard usage when expressing preference between two items.
Option (2): "He is interested on learning new languages." — The correct preposition should be "in" ("He is interested in learning new languages").
Option (3): "They were surprised of the sudden announcement." — The correct preposition should be "by" ("They were surprised by the sudden announcement").
Option (4): "She arrived to the party at 8 PM." — The correct preposition should be "at" ("She arrived at the party").
Thus, the correct answer is:
\[
\boxed{\text{I prefer coffee over tea}}
\]