Hi. I just came off of Prozac after about 2-3 years of use. I started at 10 mg and then slowly had to keep upping the dosage to get the desired effects. Eventually I got to the max recommended dose of 80 mg and it just did not work anymore. This "poop out" can happen with any antidepressant. I think Prozac is a good starting point - it did wonders for me for awhile and had very few side effects. It is also supposed to be one of the easiest to come off of because of a long half life.
(Prozac never worked for anxiety for me).