Is nefazodone or Prozac (fluoxetine) better to relax you and help you get some sleep?

Serzone/Prozac. Serzone is used to be prescribed for depression & insomnia. Prozac (fluoxetine) is unlikely to be sedating. Best to discuss with your doctor the sleep hygiene techniques or google that for more info.
Surprise answer. Don't do either! One of the commonest causes of insomnia is the inordinate intake of sugar, pop, "junk", espcially caffeine. Try adjusting your diet. Stress can be helped a lot by learning to meditate. Sounds old fashioned? Well, it is and sometimes the old beats the new. Our collective health in america is absolutely awful and mainly related to diet, overwork (or under) and other forms of stress.