I am an Indian; and Tamil is my parents' native language. However, English was spoken to me from a very young age and I think, talk and dream in English lol (got an 8.5 in IELTS). It is the language I am most comfortable with and I know it a hundred times better than Tamil.
I am planning to put in English as my "Native language" in the PR application - I will explain this in the LoE. I did put in English as my "First Language" for IELTS.