As a counterpoint, I'd argue that the "mathematical" approach to good writing is inherently flawed. That is, trying to arrive at the formula for the "best" essay via dialectic (argument) is to miss the forest for the trees. Writing is an art, not a science. Formal logic was developed to display arguments, so if you are trying to be as precise and mathematical as possible, use that instead.
Instead, I'd suggest reading the great writers of the past and present (but focus more on the past). Study what works, what speaks to you, what stylistic approach you favor, and so on. As a bonus, you'll learn more about what has been said by other intelligent people and subsequently avoid writing over-confident, ill-informed essays...
If you're looking for stellar examples of essay-writing, I personally recommend Jorge Luis Borges and David Foster Wallace. Both manage to write in a manner both erudite and coherent, without seeming too florid or too simplistic. Here are a few samples:
- A New Refutation of Time, Borges:
https://www.gwern.net/docs/borges/1947-borges-anewrefutation...
- The Analytical Language of John Wilkins, Borges:
http://www.alamut.com/subj/artiface/language/johnWilkins.htm...
- David Lynch and Lost Highway, Wallace:
http://www.lynchnet.com/lh/lhpremiere.html
- Laughing with Kafka, Wallace:
https://harpers.org/wp-content/uploads/HarpersMagazine-1998-...
- Consider the Lobster, Wallace:
http://www.columbia.edu/~col8/lobsterarticle.pdf
Edit: added some more essay links.