You have to just run down the list, checking each one, the quickest and easiest I think would be something like:
*temp highest_stat
*set highest_stat "strength"
*if agility > {highest_stat}
*set highest_stat "agility"
*if stealth > {highest_stat}
*set highest_stat "stealth"
Your ${highest_stat} is your highest stat, at ${{highest_stat}}.
Note that will favor anything at the top of the list, so if agility is 3 and strength is 3, it will return agility. If you want to check if anything is equal to the highest stat, you’ll need a few more checks. (also note you’re going to need the newest update to copy/paste the above code).