I have flown all 3 carriers TATL alot. In terms of long haul service. between the 3, I would rank AF first, DL second, and KLM last. I find AF's 777s in Affaires significantly cleaner than DL 767s + A330 BE cabins and lavatories. I have had more enjoyable + savory meals on AF, than DL, and certainly over KLM which has been so average. DL does get points for service with a smile, keeping the wine flowing ^, and great IFE. KLM, for so many reasons in my experience, continues to prove just standard, nothing special.