As a pax, a good FA is someone who if, Gd forbid it was needed, would project confidence and know the proper procedures in an emergency.

Cabin crew who actually appreciate the fact that you fold up your newspaper and take notice of them during the safety briefing! I've had quite a few on BA comment on how rare it is for a pax to do that after seeing me do it - and after becoming a ppruner, I always check the lifejacket really is there, too.