I read in both, Arabic (my native) and English. Some books are very hard for me to understand in English so I find an Arabic copy and read it. Example, The Count of Monte Cristo was very hard to grasp in English. Then I read it in Arabic and it was the best novel I’ve ever read.
I never read Stephen King books in Arabic, because doing so loses that Stephen King way of storytelling which is one of the best. He has a way of writing that no translation gives justice.
I also like to keep my native language in check so I don’t forget it.