What is the safest and most responsive medicine to get for depression?

Not clear.: The answer about the "best" medicine for depression would need to come from couble blind comparison studies of the various antidepressants. These studies typically need to be funded by nih. Individual companies fear to do these studies because if they come in second they lose market share. The best response to an antidepressant comes from taking a proper dose for an adequate time.

SSRIs: The first line medications are selective serotonin reuptake inhibitors (ssris). They are about equally effective.

That depends: Selective serotonin reuptake inhibitors for classic depression. Wellbutrin (bupropion) for atypical depression, mood stabilizers for bipolar depression. Atypical antipsychotic for a psychotic depression.