Better the Devil you know. . .
The saying: better the devil you know than the devil you dont know often creates a problem for users of English language, most especially non-native speakers. It is usually replaced with better the devil you know than the angel you dont know, which is wrong.
Better the devil you know than the devil you dont know is an idiom meaning: it is often better to deal with someone or something you are familiar with and know, even if they are not ideal, than take a risk with an unknown person or thing.