My favorite AF flight was my first, way back in 1983. A 747 from CDG to SFO, IIRC. It was in economy but the food was wonderful (a filet mignon for lunch that was the best steak I've ever eaten in my life) and I seem to remember tons of leg room. I'm probably romanticizing the experience (I was a year out of college) although I had flown a lot at that point including round the world on PanAm.
I think my first biz flight on AF was also extremely exciting, for the seat, the food and the service. Don't even remember from where to where (maybe SFO to CDG using miles) but I do remember I saved the menu and showed it to everybody I could.