Rubin, Aaron D. “The Paradigm Root in Hebrew.” Journal of Semitic Studies 53 (2008): 29-42.

The basic idea of this article: you just can't win! The choice of a paradigm root does not have a perfect solution: each root has its pros and cons. שמע has the guttural, but it has many  attested forms. Some have used שמר, but it appears in only a few binyanim and has an odd hitpael form. פעל gave names to the binyanim, but is rarely used as a paradigm. פקד is a popular choice because it appears in all 7 binyanim, although it has an odd hitpael form (Judges 21:9). Some used למד. A popular one recently has been קטל, but it is very rare in the Bible, does not use dagesh lene, and it has an unpleasant meaning. Modern Hebrew inscruction uses כתב, but it is uncommon in Biblical Hebrew teaching. The article is interesting for the view of the history of the study of Hebrew grammar.