Since no one else has chimed in, I'll give my feedback on the two. My experience with lexapro was overall positive. It helped me get over a time in my life where I was having panic attacks often. I took it for about 3 months and after the initial bumps of starting I lived normally and was able to travel and be productive.
I also have Vistril on an as needed basis and have taken it a few times. I need to dose around 75-100mg to feed a solid reduction in anxiety if I'm really wound up and at that level it puts me to sleep. It's very good for abating a panic or calming down after a stressful period. Also, it's good to take when flying as it is sedating, anti-anxiety and amazing for motion sickness. I take 25mg every 3-4hrs when flying and feel slightly calmer and avoid airplane headaches.
Best of luck, the Lexapro should do you good if you give it due time. Even if not, don't grow discouraged, there are nearly as many medications as there are types of people.