So who is the most, and least verbose Justice? Scalia has the shortest opinions for the Court, while Kennedy has the longest. RBG has the longest dissents.

The Review notes (p.415):

This is the first year that The Statistics has included data on opinion length. Monitoring opinion length by Justice will likely be useful for tracking the writing habits of individual Justices over time, as well as for comparing the writing habits of Justices in a given Term. The data in this table reflects the length of opinions as published in the Court’s slip opinions, estimated to the nearest tenth of a page. Though the slip opinions are eventually superseded by official case publi- cation in the United States Reports, the total opinion length, in pages, is generally preserved in the final publication. To obtain the average length figure, the number of pages written by each Justice was summed within each category of opinion and divided by the number of opinions of that type written by that Justice. For the number of opinions written by each Justice, see supra Table I(A). A typical slip-opinion page contains approximately 560 to 590 words.