There are many , many theories surrounding child-
development, and it would take a 20,000 word Master's
dissertation (at least) to do any justice to a comparison
of them.
I suggest that you do some 'cherry-picking', ie. select
2 credible theorists, as examples of the diversity of
approaches, and examine them critically.
Personally, I would opt for the work of Vygotsky and
Piaget, as both appear to be profoundly rational.