I agree that CDG is the worst. That said, flying from Terminals 2E or 2F is not too bad. I also agree that LHR has significantly improved since T5 opened, although I have not travelled from T4 for a long while. Athens is a pretty reasonable airport and as I travel regularly to Brussels I may be immune to its weaknesses but I think it is pretty reasonable apart from the long walk from the Schengen area to the airport exit. In my experience of 250+ flights, the time to get through security is no worst than any UK airport I’ve been through
Other airports on my worst list include Madrid and Warsaw. I’m not too fond of Zurich either. Prague is high on the best list apart from the ridiculous prices for food and drink
My wife has a different criteria for ranking airports. As she smokes she marks down airports where smoking is now completely banned inside the terminals. Amsterdam used to be her favourite airport, but not anymore and we now no longer intransit through Schiphol for long haul journeys….