Staying in an outside PG will be better than staying in Amity University Noida in campus hostel. The hostel rules are strict. Hostelers aren’t allowed to go outside of the campus on weekdays. If you need to go out for some reason, you need to complete a time-consuming application process. You can’t stay over at your friend’s place for any reason. Staying in PG will give you more freedom.
My best friend is doing graduation from here and he is in 3rd year now. So, I am quite aware of the situation.
Furthermore, don’t go for flats at all. You're a student, and you're here to have fun and study, not to start a family. Groceries, maid service, laundry, and so on are not easy tasks to maintain while studying. Enjoy your college years and choose either PGs or Hostel to stay.