I personally believe this is the #1 best Zapper out there, because it is very small and battery efficient, and very easy to use. It also has aligator clips which will clip onto any electrodes you need to use for your purpose. AND it is only $10. Which means if you need a bunch of them, you can afford it or if you are just sceptical, you won't have to spend all your good money on something you don't know if you believe in yet. I believe in Zapping, and this Zapper works just like any other Zapper on the electronics end. What ever you go with, it's awesome!
There are a number of other good Zappers on there, this is just the one I use and recommend! I hope this is helpful to you!
P.S. I don't have any experience with warts and Zapping, but I have heard stories of them going away for people after Zapping!