Note that novella are defined for Hugo as stories between 17.5 to 40 thousand words - with a margin of 20% at either end.
I order the novellas below according to my preference - better ones near the top; actually, #2 to #4 are pretty much the same quality, & can be swapped around. My rating follows the story title (in brackets). "*" marks the official winner.
- * Robert Reed's "A Billion Eves" (A); Asimov's Oct/Nov 2006: Options galore to rebuild your unhappy life, in a society not very friendly to women.
- William Shunn's "Inclination" (A); Asimov's April/May 2006: An adolescent boy comes of age.
- Robert Charles Wilson's "Julian: A Christmas Story" (A): A medieval society follows the exhaustion of earth's oil resources.
- Paul Melko's "The Walls of the Universe" (A); Asimov's April/May 2006: A boy is conned by his alter ego from a parallel universe.
- Michael Swanwick's "Lord Weary's Empire" (C); Asimov's Dec 2006: Story of an urban gang among a community of many kinds of magical creatures, & with an incomprehensible end.