AB49KThey both look good but... which one to pick first 
mike.xnx.tracy@AB49K Learn how it works before you learn how it breaks. You will find more interesting and perhaps unnoticed ways of breaking it.
@miketracy
I have experience as a sysadmin and a programmer as well as writing my own hacker challenges.
I'm mostly doing this to stretch my brain and get a few certificates lol.
@AB49K I've been doing this 20+ years and that little piece of advice has kept it fresh and fun.