I have never taken either of them so I can't help you there. But my girlfriend was on lexapro and it helped her. She can't get it now because it isn't in her insurance plan anymore. But she said she really liked it.
I hope that somebody else has posted and can help you more. Have you researched them on the internet yet? Checked out the side effects. Even if somebody does take it, it doesn't mean it will work the same for you. So the best thing that you can do is trial and error. They work differently on different people.
I hope that you find what is right for you. I have not heard bad things about
either one actually.
PS check "stillme"'s post called "finally". At the end he posts about lexapro and celexa.