I think Zinco has it right about efficacy, another part of the equation is quality of life. My experience has been that pretty much every SSRI / SNRI I tried all caused bladder problems. Sure I could have worn protection or been catherterised but both options seemed intolerable and the problem itself had a massive negative impact on both my self esteem and quality of life. Eventually, my doc found a new ad, which doesn't have that effect, however it does give me creepy feelings in my legs (like insects under the skin) but I can live with that, its unpleasant but doesn't affect the quality of my life, I'll get used to it.