Desk research against primary sources. Figures are traced to the issuing UAE authority and linked on the page.
The practical test is not which curriculum is best in the abstract but which one lines up with where your child sits their final exams and which university system receives them afterwards. British and American systems assume a return to their own higher-education pipeline; IB is built to be read by admissions offices in multiple countries at once, which is why it carries a premium even where the teaching quality is comparable to a cheaper curriculum.
Switching curriculum partway through school is harder than switching schools within the same curriculum, because the exam syllabus and grading structure rarely map cleanly onto each other. If there is any chance of relocating again during your child's school years, weigh that portability at the point of first enrolment rather than only once a move is actually on the table.