Which of these is one the most important pieces literature to come out France during Renaissance period?

It's impossible to definitively say which single piece of literature is "the most important" from the French Renaissance. It depends on what you value:

* Influence and Impact: François Rabelais's *Gargantua and Pantagruel* is a strong contender. Its satirical and humanist themes had a lasting influence on literature and thought.

* Literary Innovation: François Villon's *Testament* stands out. Villon's use of language and form, especially the "ballade," influenced poets for centuries.

* Political and Social Commentary: Michel de Montaigne's *Essays*, written during the late Renaissance, are widely considered a cornerstone of philosophical and personal writing.

Other important works include:

* Pierre de Ronsard's poetry: Ronsard helped establish the French language as a literary medium.

* John Calvin's *Institutes of the Christian Religion*: Though a theological work, its impact on Protestant thought was immense.

Ultimately, choosing one "most important" piece is subjective. All of these works offer valuable insights into the French Renaissance and its influence on Western culture.