It's tricky to define "the best" of any author definitively, as it depends on personal preference. However, I can offer a review that touches on the breadth of Harry Turtledove's work and highlights some of his recurring strengths: Harry Turtledove is a master of alternate history, and The Best of Harry Turtledove would have to showcase his ability to craft intricate and compelling "what if" scenarios. His work is often action-packed, plunging readers into vividly realized worlds where pivotal historical moments have taken a different turn. Whether it's the Civil War with advanced weaponry (The Guns of the South), World War II with alien invaders (Worldwar series), or a prolonged and altered Great War, Turtledove excels at exploring the ripple effects of change on societies, individuals and the course of history. His novels are known for their detailed world-building, diverse casts of characters and a knack for blending historical accuracy with imaginative speculation, making him a captivating and thought provoking author.