Xanax (alprazolam) or celexa (citalopram) which is better for panic attacks and which has worse side effects or more addicting? thank you!

It depends: Celexa is better for long-term treatment/prevention of recurring attacks, and actually works well (as do other ssris, like paxil, (paroxetine) prozac, etc.). Xanax, on the other hand, is better for acute attacks, to be taken when you're actually having an attack. It's better not to take it all the time if possible, as it is a controlled substance, and, thus, more addicting.