In terms of methodological quality, "Fixing Faults in C and Java Source Code: Abbreviated vs. Full-Word Identifier Names" [0] is a favorite of Hillel Wayne's [1].

> Manageable scope.

> They did their homework.

> They mix qualitative and quantitative methods.

> Objective measure of Defects.

> Really, _really_ good experimental setup.

> And then an ethnography.

[0] http://www2.unibas.it/gscanniello/Giuseppe_Scanniello%40unib...

[1] https://www.hillelwayne.com/post/the-best-se-paper/