I agree that I've had had good and bad crews in both cabins on all of the skyteam partners.

I would generalize to say that US based crews can be warmer and more homey, while European crews seem more professional, so some of it is subjective.
(I actually seem to get along better with AF crews than many American's report - maybe because I speak the language.)

The one difference that makes me more comfortable on DL metal than on AF/KL metal is that I feel like if things are really bad, I know that a complaint to DL after the fact will (eventually...) result in some sort of response or gesture that acknowledges the experience and gives me the sense that someone has heard me and may actually take action.

I've simply never had that happen on AF or KL and it makes the bad experiences even more frustrating knowing that no one gives a damn...