As a pharmacist, I have to say that in many patients the SSRIs and SNRIs are considered to be equally effective. The individual agent is often chosen based on the individual patient and the drug's side effect profile (some are more activating, some cause more sexual dysfunction, etc.)
The same can be said with anti-psychotics. All have been shown to be equally effective, with the exception of clozapine, and are, again, often chosen based on side-effect profile (changes in lipids, glucose, weight gain, extrapyramidal effects, etc.)