Constructivism is alwasy the foundation of any research that has beed done to ESL students-education sectors; however, post-positivism seeks to understand how human and social interactions may influence treatment outcomes- medical sectors.
I prefer constructivism. Because student is the main body of the teaching process. By observing students different personalities, we could transform the model of teaching. Also, Constructivism is a good way to promote teahing innovation.
Which paradigm to choose depends on the values of the researcher, it depends on the researcher's understanding of the purpose of the study and the perception of the participants in the study. I think it's available to choose research methods based on value beliefs.
The post-positivism paradigm emphasizes existence and reality, while constructivism is relatively flexible, which takes into account the diversity of participants and taking into account different demands and cognitions.
For the learning and education of minors,maybe the flexibility of methods is more important.