Dr. wants to put me on ssri either lexapro (escitalopram) or celexa...mainly for anxiety/panic..which is better. ?

Many factors: Work with your doctor. If you have family members (parent or sibling) that had a good response to one over the other, that is a good place to start.

They are both good: medications made by Forrest Industries. One is a racemic mix and other is cleaved. At a lower dose the lexapro (escitalopram) may have potential for lesser side effects but as dose increases this becomes less so.