Of the major "western" carriers I've experienced more than once, I don't see much difference. One flight can be solid, and then next a bit sketchy, on Delta, or AA, or United, or whoever. Air France USED to have better food, I thought, but I think now they source the same as Delta. We both "like" Delta, which is a good thing considering where we reside. They get it done.
My usual calculation is how much to pay extra to get into a better class seat. It used to be "Economy Comfort" for the extra leg room.
I still don't really understand how ticket prices can vary wildly over day of the week or whether it's nonstop or not. I guess business travelers tend to fly out on Monday etc.
We used to get "first class" flying to Europe at work, they only had two classes back then, now there are at least four.
