BEST: KLM/Copa/Continental hands down. I cant remember names but most of the time they are all super friendly and warm. However, once on a PTY-IAH flight in F, one of the F/As remembered me from previous flights and welcomed me back by my name and was extremely friendly and attentive during the flight.
Bad: (Air France mostly, some Continental) Well I never really had bad experiences but sometimes there are a few F/As who no matter how much I try to be nice or friendly they are just so cold and unwillining. It is very obvious that they are having a bad day and/or just hate their job!!....
Weird experiences: Well twice in the past I had male F/As flirting with me perhaps to check out my reaction if i was interested. Because I am straight I didnt flirt back and remained polite but the F/A would continue flirting (nothing gross or too strong, but still kind of akward).
In summary, the very best F/As are the ones who love their job and when they do, it reflects on them and passengers can see this and the trip is always great!!