Yesterday I wondered why Rich Horton chose my story "Art of War," rather than another story of mine, for his Best Of The Year. Today I know, because Rich read my blog and sent me email about it. With his permission, I'll both quote and summarize what he said:
"I typically have a longish list of stories I think are plenty good enough to go in the book -- the hard part is leaving some out. There might be four or five that are among my absolute favorites that I think I have to have -- but beyond that, I like all the stories similarly, so other factors really are appropriate." He goes on to name those other factors:
contractual availability -- "Each year so far there has been one story I couldn't take because of contractual restrictions."
varied representation -- "I restrict myself to one story per author."
length -- Although "it's important to have a variety of lengths," shorter stories leave more room for other good work and so may have an edge.
varied sources -- Rich tries to not "take too many stories from the same source -- Asimov's, for instance."
varying tone -- "It's nice to have at least some lighter stories in the mix" -- and varying subject matter.
There you have it, fellow SF people -- editing is a balancing act. Not unlike writing itself.