I've now done alot of them: NW(old & New all aircraft), KLM (not new 777), CO 767-300, DL 767-300er, AZ 767, CSA A310

Here is what I think:

# 1 CO - for best overall experience - yes the pitch is only 55" but the food and attitude was great. Also note that AZ and CO only put 5 seats accross ont thier 767's where DL (and KLM) have 6 accross -makes a HUGE difference.

#2 NW 330 - mainly because I can sleep on those seats and the AVOD is way cool. Food is not very good though.

#3 KLM/AZ KLM seats are nicer but the food on AZ is better - though I know many would not be happy about the lack of AVOD on AZ

#4 CSA - small seats and not great pitch but very nice food.

#5 DL /KLM 767- those 767 seats suck, and the food is not very good.

I understand what you mean by "experience" and that is why, to me CO is the best of what I have tried. Please also note that I have not flown AF so I cannot give you much information for them.