Hey tammy,
i dont know anything about klonopin, xanax, or lexapro, but i take 150mg Effexor-xr daily just been increased from 75mg about a month and a half ago,as 75mg wasnt doing anything for my anxiety/panic attacks, but since taking the 150mg ive been able to go further outside and actually feel like doing things again, and in situations that i used to get panic attacks i find now i can control/only get mild anxiety. So in my opinion Effexor is really good, but in saying that everyone is different, so i guess youll have to see how things go for you.
All the best hope things go well for you..
((((((((HUGS)))))))) to all..