Post-traumatic stress disorder. It's a popular diagnosis now. So, what is the best med for it?

It depends... . The treatment of choice for ptsd involves centrally psychotherapy: essentially, making peace with the fact that the trauma happened and that the universe is still, for the most part, a safe place. Meds may or may not be needed as adjunct to therapy... Also, the actual clinical presentation (and it varies) will determine the medicine of choice.
That depends. Selective serotonin reuptake inhibitors are usually the first go-to medications. For marked dissassociation (i.e., flashbacks) atypical antipsychotics may be necessary. Sleep is a major problem. The combination of nightmares & insomnia may respond to off-label use of prazosin. Cognitive processing therapy is the gold standard for working through issues.
It depends. Posttraumatic stress disorder occur after life threatening event. A detailed history, medical, neurological & psychiatric evaluation is done to develop a treatment plan. If the findings are mainly psychiatric symptoms, cognitive-behavioral therapy and marital therapy, with ssri medications (celexa, zoloft, (sertraline) Prozac etc) help. Patient's need evaluation for symptoms that frequently develop later on.
Zoloft (sertraline) &Paxil --FDA. They have fda indicaton but, in my experience meds not major role--de-conditioning peer interaction family support all imprtant.