What fill power should I look for in a down comforter?

Most mainstream reviewers point to roughly 600–800 fill power as the sweet spot for a luxury-feeling down comforter. The Brooklinen All-Season in this ranking uses 700 fill power, which The New York Times' bedding coverage cites as a reasonable benchmark for warmth-to-weight. Higher fill power means lighter, loftier insulation but rapidly diminishing returns above 800.