I've flown on KLM in J 6 or 7 times in the past year, and I've done AF in J once on the 380 a few weeks ago (the 777 to DEL was 2 years ago now).

On the whole, I was pretty underwhelmed by my experiences on AF. While I did appreciate the decent selection of movies and a delicious amuse-bouche, I found the 380 J seat uncomfortable as all get-out for sleeping (not to mention feeling super close to my neighbor). What's strange is that I don't remember finding the 777 seat as awkward, although I was coming off of a red-eye on the old DL 757 recliners, so maybe it's all relative. I do remember the screens on the 777 being on the small side, as well. The new AF J product looks encouraging, at least.

KLM would be my preference over AF, although there's a pretty considerable comfort difference between the new and old WBC product. The new WBC has some truly comfortable seats that lie fully flat, but I'd advise a seat in the center section in that event so as to avoid climbing over someone (or vice-versa). On the other hand, every time I've been on a refurbished new WBC aircraft, the entertainment either had to be reset multiple times (or flat out didn't function). KLM crews are generally a little more proactive and attentive than those on AF in my experience. Food on KLM is solid -- nothing particularly fancy, but they've tended to be dishes that translate well to being in the air (stews, cuts of meat that are suitable for braises, etc.). Wines have, however, been pretty pedestrian as of late.