Ecco's book [translated by Andrew Bromfield] has one possible selling point for a novel infamous for its length: It's more than 400 pages shorter than the so-called canonical version, in part because it lacks many of the philosophical digressions and historical observations Tolstoy added later. Also, its story has some twists, since Tolstoy changed the fates of some characters, including killing off several between drafts.
Faced with this sort of choice, my inclination, at least for my first go round, is to go with whichever version the author regarded as the final work. But according to an expert quoted at the conclusion of the article, Tolstoy himself never expressed a clear view on that point:
"There is no definitive edition," says New York University's Anne Lounsbery, assistant professor and director of graduate studies in the department of Russian and Slavic Studies. She adds, "Tolstoy himself didn't take much interest in it after he wrote it. He allowed interventions by all sorts of people."
I'm still inclined to think that the Pevear and Volokhonsky translation is the one for me, but perhaps I ought to undertake a bit of research before making the final call. Certainly the foregoing indicates what a complicated business selecting a translation can be.