Well I have taken both. Xanax stopped a panic attack for me and brought my pulse down from 150 to 100 within just 10 or so minutes, but I've heard from 3 doctors that it's super addictive and eventually it won't work as well for me unless I take more, then more, then more, etc. My last panic attack (in January), I was prescribed Valium. It worked really well for me too. I only took it when I absolutely had to, and I would still be taking it if I weren't pregnant. It definitely calmed me down an helped me relax, which helped me sleep too. I hope I've helped some :)
I like xanax but I only use it when I'm absolutely at my worst because, as vbilger said, it's pretty addictive stuff if you use it regularly. It works really fast when you are having a bad attack. Best wishes in finding the right combo.
I take xanax as needed for panic attacks. It really helps if I'm having a horrible one and can't calm myself down. They're great for random panic attacks. If you don't have constant anxiety then they work well. If you're anxious everyday then something more long term would be better. Klonopin is another benzo that stays in your system longer so its better for long term regular use.
Good advice from the above, but keep in mind that alcohol ramps up our anxiety, making it worse. Since you don't have constant anxiety, therapy may be a better choice for you than medication. I would see a psychiatrist and go from there. The two of you can then decide the best course of treatment for your needs....therapy and/or medication. Therapy would address your fear of dying, and once you do this....your anxiety may be non-existent. I hope this helps and best of luck to you!