Which church was told, "I know your affliction and your poverty—though you are rich"?

Answer: Smyrna

Smyrna was poor yet rich. (Laodicea was the opposite: it claimed to be rich but was poor.)

“To the angel of the church in Smyrna write: These are the words of the First and the Last, who died and returned to life. I know your affliction and your poverty—though you are rich! And I am aware of the slander of those who falsely claim to be Jews, but are in fact a synagogue of Satan.”— Revelation 2:8-9 (BSB)