In all seriousness
This is a actually really good thread and I have often tried to think of what would constitute "favourite cabin crew", and hence coming up with things that I could bring to the table during feedback/workstream meetings.
Just like "what is your favourite airline", so many things are taken into account. For example, I have been SLF on many airlines. If the flight is on time, food is served timely and looks good, and my seat is not broken and my IFE system works, then that is a really good flight! So naturally, I would say all aspects are good including cabin crew. So it is only when there are problems that you can really see how good the cabin drew are.
Earlier I said that Singapore have the best cabin crew. But I have never had any problems on a Singapore Airlines flight. But the cabin crew are so welcoming, friendly faces - glowing faces and they seem to have genuinely friendly smiles. Now perhaps this is a psycolgical thing - I'm sure there are psycologists that have worked out what is a naturally friendly face that all humans are instantly attracted to (in terms of feeling at ease, comforted, trust etc).
And perhaps the reason people say Singapore, and a few middle eastern airlines is because the cabin crew are mostly from South-East asia like philippines, thailand etc and perhaps they just have the "right" face. So the moment you meet this cabin crew, they already have points in the bag because immediately you feel at ease.
On the other hand, I can think of a few english colleagues in my present work that are so friendly and sociable but they always look like they have just had an argument with their bf/husband! They just can't help it. So from a pasenger point of view, that is not a good advertisement for the airline. And this is perhaps why european airlines do not feature so high in people's opinions.
I also believe that the uniform has a very big importance and I am surprised when I see other airline's cabin crew because surely every airline must employ a fashion designer who has experience with knowing what colours give the right impression and what style - again we are back to the psycological reasons.
I honestly believe (and I'm trying not to be biased here) but Virgin really do look the best. The striking red colour but also the style. It is extremely smart and has great lines and I think people really to take to it well when they see a group of us walking in the airport. I hope I haven't started an argument!