No one can be "genuinely happy" all the time because happiness is a transitory, at the moment, type of emotion, like pleasure, joy or euphoria. And if you were to be actually found smiling constantly 24/7, its a pretty good bet that you've got some fairly serious mental health or wiring issues that need to be addressed.
However, we all can be "genuinely content" with our lives. This because its a reflective feeling that does not need external stimuli for it to be generated. Helping us to look back at our lives and feel good about the decisions we've made.
Now, are Witnesses more "genuinely content" than worldly people? If a survey was honestly held, I'd expect not. As nearly every brother and sister in the Kingdom Hall I've met in my life, has expressed in either word, action or facial expression, their tiredness of the Theocratic grind, while longing for the bus to paradise that never comes.
Where as "worldly" people on the other hand, having same family, health and financial pressures as JWs, enjoy the extra freedom and time to express their personal wishes, in a fuller way.
no zombie